Republicans were already at a massive disadvantage when it came to the 2016 Senate map — defending more than double the number of seats as Democrats. To compound matters, many of those endangered Republicans were sitting in swing state territory in a presidential year where the electorate already leans more liberal.
Donald Trump's once-sagging poll numbers rebounded nationally after cratering post-convention. He's doing better now in battlegrounds where he needs to win the White House — and where Republicans are defending their toughest Senate seats — but overall still narrowly lags Hillary Clinton.
Some Republican seats once thought to be sure-wins for Democrats, such as Ohio and Florida, are moving off the table. But now, seats in typically safe GOP turf, such as Indiana and Missouri, are at real risk of flipping. It's a much different path to the majority than either party had expected.
But ultimately, two months away from Election Day, there are plentiful pick-up opportunities for Democrats to get to the five seats they need (or four with a Clinton victory) to win the majority. Many of the races have tightened — and Republicans are still very much in the game — but it's increasingly looking like a narrow majority for Democrats is the most probable outcome.
Here are our latest ranking of the Senate seats most likely to flip on Nov. 8. Check out our previous rankings here.
1. Illinois (R-Kirk) Previous rank: 1
Mark Kirk has tried his best to separate himself from his party's nominee. In May, he became the first GOP senator up for re-election to withdraw his endorsement of Donald Trump after the Republican nominee made derisive comments about Mexican-American Judge Gonzalo Curiel. He followed that up with an anti-Trump TV ad touting his independence. When Trump met with Senate Republicans last month, he singled Kirk out as a "loser" and predicted he would carry the state in the presidential race. The reality is that Trump will surely lose the heavily blue state in a landslide. While Kirk will run ahead of him, the already hostile climate coupled with a good candidate in Democratic Rep. Tammy Duckworth make it nearly impossible for him to continue his previous streak of unlikely wins on blue turf.
2. Wisconsin (R-Johnson) Previous rank: 2
Most Republicans agree the next incumbent most likely to lose is Wisconsin Sen. Ron Johnson. A recent Monmouth University poll gave former Democratic Sen. Russ Feingold a double-digit lead in his rematch with Johnson, though the well-respected Marquette University Law School poll gave Feingold a much slimmer 4-point advantage. Unlike some of his other endangered Republican colleagues, the first-term incumbent hasn't moderated many of his stances. Koch-backed groups cancelled their planned ads to help boost Johnson, though they did go back in early in August. Still, the national party has delayed ads as well. Overall, the writing on the wall isn't great for Johnson.
3. Indiana (R-open, Coats retiring) Previously not ranked
Republican Sen. Dan Coats announced in 2015 that he would not seek re-election. The biggest surprise of the cycle was former Democratic Sen. Evan Bayh's decision to make a late entrance into the Senate race despite multiple, often forceful, denials he was interested in returning to politics. He's the only Democrat in the state who could have put the race into play. Republicans hope the statewide ticket is boosted by Trump's running mate, Indiana Gov. Mike Pence, though he has a middling approval rating in the state.
By all accounts, the famed political scion remains popular in the state. But like former GOP Sen. Richard Lugar, he's been beset by questions about his residency, and Republicans are hammering him on just how much time he's spent there since he decided to retire in 2010. He moved to a $2.9 million house in Washington and worked for a lobbying firm, and he was deemed an "inactive" voter. In interviews, he's stumbled to recite his Indianapolis address, and neighbors say they never even knew he lived there.
This race is just beginning to engage, and too many missteps may have already wiped away Bayh's early advantage. He started out with a double-digit lead, but a poll Friday from WTHR and Howey Politics, the most widely read political blog in the state, showed Bayh is only up 4 points. GOP Rep. Todd Young still has to introduce himself to voters, but Bayh can't take his triumphant return for granted.
4. Pennsylvania (R-Toomey) Previous rank: 4
GOP Sen. Pat Toomey has done plenty to try and bolster his centrist credentials. One of the leading Republicans calling for gun control, he was endorsed by former Rep. Gabby Giffords' group, Americans for Responsible Solutions. He's been critical of Trump and has withheld his endorsement. The Keystone State is a place where Trump had hoped to make gains, given its white working-class population. Most recent surveys show former state environmental chief Katie McGinty edging him out narrowly, but a Quinnipiac poll on Friday gave him a 1-point lead. McGinty had some unforced errors after she won the April primary that raised some questions about the discipline of her campaign, but Democrats say those are behind her. Toomey isn't doing well with the suburban voters he needs to win over, and he's got to make up ground there to have a chance to hang on.
5. Nevada (D-open, Reid retiring) Previous rank: 7
This is Republicans' lone offensive opportunity, and it's increasingly becoming a must-win if they want any hope of keeping the Senate. Despite the state's sizable Hispanic population, Trump is holding his own in Nevada — and by extension, so is GOP Senate nominee, Rep. Joe Heck. Recent polls have been within the margin of error, but Heck hasn't trailed in a poll since May. But with Hispanic registration surging in the state, Democrats hope Clinton will soon open a wider lead that helps former state Attorney General Catherine Cortez Masto. And the vaunted turnout machine of retiring Democratic Senate Minority Leader Harry Reid has helped win close contests before.
6. New Hampshire (R-Ayotte) Previous rank: 3
The Granite State contest is one of the most consistently evenly matched races this cycle in the only race between two women. For much of the year, incumbent GOP Sen. Kelly Ayotte and Democratic Gov. Maggie Hassan seemed to be pretty evenly matched. An NBC/Marist poll released Sunday showed Ayotte opening up an 8-point lead, though that large a lead could be an outlier. Democrats have hit Ayotte for trying to have it both ways of sorts with the top of the ticket remaining critical of Trump and saying she won't endorse him even though she is supporting her party's nominee. That waffling led Trump to criticize her in an interview with The Washington Post last month — something that may be more beneficial to her campaign. He eventually relented and has endorsed her. Trump also hasn't spent any money on-air here yet, and Republicans worry the TV edge Clinton has will help Hassan. This race has seesawed back and forth between the two for the past year, and the presidential contest will have a huge impact.
7. North Carolina (R-Burr) Previous rank: 9
Republican Sen. Richard Burr has been slow to shift into high gear for his tough re-election challenge. He has barely been campaigning — and even told the AP he doesn't see himself as a candidate until October when the Senate adjourns. His Democratic opponent, former state Rep. Deborah Ross, has outraised him in recent filings, and she's looking to piggyback not just on anti-Trump sentiment in the state but also the general sour mood of the state GOP in North Carolina, after many controversies in the general assembly, including the so-called "bathroom bill." Republican Gov. Pat McCrory trails for re-election, so that's another complication for Burr. National Republicans have been working to paint Ross as too extreme, pointing to her time as executive director of the state's ACLU. But Burr has a real race on his hands — a Quinnipiac poll only gave him a 4 point edge — and he hasn't seemed to fully grasp that yet.
8. Florida (R-Rubio) Previous rank: 6
What was once one of Democrats likeliest pick-ups evaporated when Sen. Marco Rubio decided to run for re-election after all. He was humiliated in the state's GOP presidential primary just months before, but he easily beat back a primary challenge from wealthy homebuilder Carlos Beruff. Democrats also got their preferred nominee, centrist Rep. Patrick Murphy, instead of controversial progressive Rep. Alan Grayson.
Even though Murphy survived the primary, he has plenty of his own troubles to overcome. The Miami CBS station aired a devastating two-part story on how Murphy had inflated and exaggerated key pieces of his background, including being a CPA (he was licensed in Colorado, not Florida) and his how many contracts for the Gulf oil spill his environmental clean-up company received.
Trump has climbed back in Florida, but even before that Rubio had continued to consistently hang on over Murphy in several recent surveys. Democrats hope that some of the same issues that hurt Rubio in his White House run, including his high absentee rate from the Senate, will be salient again. And they're painting him as someone who's already looking ahead to another presidential bid in 2020 and not fully committed to serving out his term.
9. Missouri (R-Blunt) Previous rank: 8
The Show-Me-State contest has gotten tighter, although GOP Sen. Roy Blunt continues to hold a slim lead in recent polls. Democrat Jason Kander, a young Afghanistan veteran, remains one of their best recruits who increasingly worries Republicans. Republicans also privately say Blunt hasn't grasped the seriousness of the threat, and was even spotted in D.C. at a farmer's market during the August recess instead of pounding the campaign trail back home. In a year for Washington outsiders, Blunt can't shake his insider status. The presidential race has tightened here too, giving Kander another boost, and national Democrats just bought ad time here. It's a race Democrats are increasingly optimistic about while Republicans are increasingly pessimistic.
10. Ohio (R-Portman) Previous rank: 5
Right now, Portman looks like he will survive any down-ballot drag from Trump. He was out early defining himself thanks to his $13 million war chest, and he's picked up several high-profile union endorsements too. He hasn't separated himself from Trump much though — he's said he would be open to campaigning with him this fall and he did attend the Republican National Convention in Cleveland even as the state's GOP governor, John Kasich, publicly boycotted Trump's coronation. But Strickland hasn't caught fire the way Democrats hoped he would, particularly with blue collar, downstate voters — the same voters Trump needs to win. National Democrats and outside groups are cancelling ad buys on Strickland's behalf — never a good sign, even though they could go back in. But there seems to be brewing frustration with Strickland, too. "Portman has run a damn fine race...The rest, I'll have to tell you over a drink," the executive director of the Senate Democrats' campaign arm reportedly told a trade group.
Honorable mention: Arizona (R-McCain) Previous rank: 10
Sen. John McCain easily dispatched with his primary challenge this week, but a tougher opponent looms in Democratic Rep. Ann Kirkpatrick. Republicans admit she shouldn't be underestimated, and she's consistently won tough races in her swing district. But they have to be breathing easier with an NBC/Marist poll over the weekend that showed McCain up 19 points. Still, the state is closer than it should be in the presidential race — Trump only led by 1 point in the same poll — and Clinton opened field offices there last month. Arizona has also seen a spike in Hispanic registration. The 2008 presidential nominee has reluctantly endorsed Trump though he has obvious disdain for him. Unfortunately, he needs the Trump conservative loyalists in the state in order to be victorious as well. For now, Democrats may focus on better pickup opportunities.