(CNN) With a little more than four weeks until Election Day, the Senate map is now tilting in Democrats' favor and even more Republicans in once-red House districts are feeling the heat of changing demographics and the weight of a President who remains deeply unpopular in the suburbs.
That's according to the latest House and Senate race ratings changes from Inside Elections with Nathan L. Gonzales, a CNN contributor.
Inside Elections shifted three Republican-held Senate seats in favor of the Democrats: Maine, North Carolina and South Carolina. Whereas Democrats are now favored in the first two contests, Republicans still have the advantage in South Carolina, but the race looks far more competitive for Sen. Lindsey Graham than it did several months ago. Thursday's changes mean that four GOP-held Senate seats are now Tilt Democratic races, which is good news for a party that needs a net gain of four seats to flip the chamber -- or three if Joe Biden wins the White House, since the vice president breaks ties in the Senate.
Interactive: 2020 Senate race ratings
It's hard to predict exactly what effect the Supreme Court vacancy and looming confirmation fight will have on specific down-ballot races, but if there's one Republican incumbent who's undoubtedly in a tough place on the issue it's Sen. Susan Collins of Maine, whose 2018 vote for Justice Brett Kavanaugh turned off moderate and independent voters and helped raise millions of dollars against her. The four-term senator was quick to say she'd oppose confirmation of a Trump nominee before Election Day, but that position isn't likely to redeem her among voters she alienated two years ago, while potentially weakening her support with the conservative voters she needs to turn out for her. Democratic state House Speaker Sara Gideon, meanwhile, has been reminding voters that the Senate race isn't just about the well-known incumbent, it's also about Senate Majority Leader Mitch McConnell and whether he stays in power.
Inside Elections shifted Collins' race from Toss-up to Tilt Democratic -- a reflection not just of her Supreme Court conundrum, but also of the reality of running as a Republican in a state where Trump is not likely to do well and where ranked choice voting potentially complicates her path to victory. Recent polling, for example, has shown Collins below 50% -- a mark she needs to hit if she's to avoid triggering ranked choice voting, which ultimately cost New England its last House Republican when Bruce Poliquin lost in 2018.
It's a similar, but somewhat different story in North Carolina, where Inside Elections shifted freshman Sen. Thom Tillis' race from Toss-up to Tilt Democratic. President Donald Trump is still competitive here, and Republicans hope a Supreme Court vacancy will energize conservatives who have been slow to coalesce around Tillis. But the senator hasn't been holding his own in polling against Democrat Cal Cunningham, a former state senator and Army reservist.
Cunningham announced Thursday afternoon -- after Inside Elections had already shifted the race -- that he had raised $28.3 million in the third quarter of the year -- a staggeringly high amount even for a Senate candidate in one of the most expensive states in the country. Tillis sided with his party -- and broke with five other vulnerable Republicans -- on Thursday by voting against a Democratic proposal to protect those with preexisting conditions from a Trump administration lawsuit before the Supreme Court next month.
The trajectory of South Carolina's Senate race may be the most surprising of the cycle. Even with Democrat Jaime Harrison raising impressive money and generating national buzz, Graham was in a Solid Republican race until mid July. Two months later, just before Justice Ruth Bader Ginsburg's death, Inside Elections shifted the race from Likely Republican to Lean Republican. And now, it's shifted again -- this time, to Tilt Republican, which is just one position away from Toss-up.
That's an extraordinary position for the chairman of the Senate Judiciary Committee, who's running for a fourth term in a state Trump carried by 14 points, to be in less than five weeks from the election. His backtracking on his own comments about not confirming a Supreme Court nominee during a presidential election year may be angering some voters, but his prominence in the confirmation hearings could also endear him to conservatives who may have been on the fence, either about voting for him or voting at all.
Perhaps the biggest sign the race is competitive is the investment of the leading super PACs on each side. Several days after Senate Majority PAC, a Democratic group, launched a $6.5 million investment in the state, its GOP counterpart, Senate Leadership Fund, said it planned to spend $10 million boosting Graham.
Interactive: 2020 House race ratings
Republicans continue to struggle in the suburbs, which is helping Democrats expand the House battlefield. Inside Elections moved eight districts in favor of Democrats and four in favor of Republicans on Thursday.
Democrats won a net gain of 40 seats in 2018, and they're defending many of those seats this year. Republicans -- who need a net gain of 17 seats to win the majority -- see their path to victory running through the 30 districts held by Democrats that Trump carried in 2016. But there are now more GOP-held seats rated as Toss-up than Democrat-held seats, with longtime Republican strongholds like Indiana's 5th District and Michigan's 3rd District sliding into the Toss-up category.
That Indiana district, currently represented by retiring GOP Rep. Susan Brooks, is a prime example of how the House landscape has shifted. This is the first election cycle the Democrats' campaign arm has even targeted the seat, which includes the suburbs north of Indianapolis. But younger, more well-educated and moderate voters have moved into the district, and it's now moving away from Trump, despite him carrying it in 2016. Missouri's 2nd District, represented by GOP Rep. Ann Wagner, also moved toward Democrats because of the dynamics in the St. Louis suburbs, where Trump may be a drag on down-ballot Republicans. Inside Elections moved the race from Lean Republican to Tilt Republican.
Two Texas districts moved in favor of Democrats for similar reasons. The 7th District, where freshman Democratic Rep. Lizzie Fletcher is running against one of the GOP's star recruits, Iraq War veteran Wesley Hunt, now looks safer for Fletcher given the national environment and how it's playing in west Houston. It shifted from a Lean Democratic to Likely Democratic race. The 3rd District is coming on the board for the first time this cycle, with Inside Elections moving it from Solid Republican to Likely Republican. The district's high concentration of college-educated voters could make it competitive for a Democrat.
Highly educated suburbs north of Phoenix are also making Arizona's 6th District competitive for Democrats, with Inside Elections moving the race from Lean Republican to Tilt Republican. It helps that GOP Rep. David Schweikert, the five-term incumbent, has had ethical issues, while Democrat presidential nominee Joe Biden and Senate nominee Mark Kelly are doing well in the state.
Not every district moving toward Democrats is Republican-held. Michigan's 3rd District, which shifted from Tilt Republican to Toss-up, is represented by retiring Rep. Justin Amash, who left the Republican Party last year and briefly explored running for president as a Libertarian. National Republicans have long been eager to take back this district, which voted for Trump, since Amash wasn't a reliable vote for party leadership in the House. But despite his personal money, Republican Peter Meijer -- whose family owns a prominent grocery store chain in the district -- is now in a competitive race with Democrat Hillary Scholten.
Republicans still have an advantage in Virginia's 5th District, but it's another longtime red district where Democrats are competitive this year. Like Michigan's 3rd District, this one is an open seat -- but for very different reasons. GOP Rep. Denver Riggleman lost the nomination at a district party convention to a Republican who initially didn't even make the ballot and has few resources compared to his Democratic opponent. The race moved from Likely Republican to Lean Republican. But outside GOP spending could still help keep this one in the GOP column.
Candidates matter. That's the lesson in Colorado's 3rd District, where Lauren Boebert's surprise primary upset over five-term incumbent Rep. Scott Tipton has put this seat in play. Boebert, who has talked up QAnon views in the past, may be turning off some GOP voters, while Trump's struggles in Colorado may mean he won't win the district by as much as he did four years ago. The race moved from Likely Republican to Lean Republican
Four districts moved away from Democrats, including two districts that Clinton won in 2016. Former GOP Rep. David Valadao is trying to win back his old seat in California's 21st District. His loss there to Democratic freshman Rep. TJ Cox, who's been pummeled with GOP attacks this year, was among the closest in the country in 2018. Inside Elections shifted the district from Tilt Democratic to Toss-up. Pennsylvania's 1st District -- an elusive Democratic target in years past -- shifted from Tilt Republican to Lean Republican. There's little question Biden will do very well here, but that may not be enough to sink GOP Rep. Brian Fitzpatrick, who has a history of overperforming the top of the ticket.
And two Democratic incumbents that were in Solid Democratic races are now facing more competitive contests. Oregon Rep. Peter DeFazio, a 17-term incumbent, isn't used to tough contests in the 4th District, but he's facing young veteran Alek Skarlatos, a who has a compelling profile after stopping a terrorist attack on a Paris train. The race is now Likely Democratic. In Wisconsin, Republicans are eager to take out Democratic Rep. Ron Kind, who's defending a Trump district. It moved to Likely Democratic, although Trump may not do as well here this time.