We can stop obsessing so much about how Sens. Susan Collins and Lisa Murkowski are going to vote. Long the crucial swing votes in the U.S. Senate, they will still be crucial to the GOP’s majority, but for the next two years, when the Senate considers legislation that Democrats unanimously oppose, the real deciders are likely to be Cory Gardner and Mitt Romney. (And maybe Martha McSally.)

With Cindy Hyde-Smith’s win in Mississippi this week, the next Senate is set: Republicans will have 53 seats in the 2019-2020 session, up from their 51 in 2018. The Democrats, of course, control the House now, so big conservative bills like repealing the Affordable Care Act aren’t likely to become law. But the Senate still approves Cabinet appointees and judges. Those votes should be easier for Republicans to win next year. With two extra votes to spare, nominees can be approved even if both Collins and Murkowski oppose them. And three of the other Republicans who have voted against President Trump’s position the most often, as measured by our Trump score, won’t be in the chamber in 2019: the late John McCain and retiring Sens. Bob Corker of Tennessee and Jeff Flake of Arizona.

So who will emerge as the key swing votes in the Senate? Among sitting members, our Trump score suggests that Kentucky’s Rand Paul is actually the most anti-Trump Republican in the chamber, opposing Trump initiatives about 25 percent of the time. Then, aside from Collins and Murkowski, Utah’s Mike Lee and Nebraska’s Ben Sasse have broken with Trump the next most often among returning GOP senators. (Note that while our metric is called the “Trump score,” the president’s position on issues that come up for votes in the Senate nearly always aligns with the position supported by Majority Leader Mitch McConnell and the rest of the Senate GOP leadership.)

But when I looked at the times Lee, Paul and Sasse voted against the Trump position, it was often on spending bills that overwhelmingly passed the Senate. In those cases, their opposition was basically meaningless. It allows them to claim that they are the among the most fiscally conservative Republicans in Washington, but it doesn’t actually stall legislation and potentially annoy McConnell or Trump.

Romney, I think, might be willing to vote against Trump’s positions on big issues. He has considerably backtracked from a 2016 speech in which he attacked Trump more harshly than even many Democrats did back then, but the Utah senator-elect is still putting distance between himself and the president. Moreover, Romney won’t have much of an electoral incentive to toe the line. He’s 71 years old, and after two unsuccessful presidential runs, I doubt he is going to seek the Oval Office again, so he doesn’t have to worry too much about pissing off the national GOP base. And Trump isn’t well-liked in Utah, particularly considering it’s such a red state. The president had a -2 net approval rating there in October, according to Morning Consult. Romney, on the other hand, won his Senate election by a hefty margin, and nearly two-thirds of voters in the state said they’d like to see him stand up to Trump, according to a recent poll, so he likely has a lot of room to oppose the president without endangering his seat.

Colorado’s Gardner has a more obvious reason to potentially vote against controversial Trump appointees and judges: political survival. It’s hard to see Trump winning Colorado in 2020 — he lost there by 5 percentage points in 2016. When Gardner is up for re-election in 2020, he will likely need some Democrats or independents to back him even as they vote against Trump. And at least right now, it would be hard for Gardner to separate himself from the president: He backs the Trump position 91 percent of the time. And, among the 100 current senators, he is tops in voting with Trump more often than the political ideology of his state would predict.

Gardner votes with Trump more often than expected Sitting senators by the difference between their actual and predicted Trump scores TRUMP SCORE MEMBER ▲ ▼

STATE ▲ ▼

Actual ▲ ▼

predicted* ▲ ▼

PLUS-MINUS ▲ ▼

Cory Gardner CO 91% 44% +47 Dean Heller NV 92 49 +44 Marco Rubio FL 96 55 +41 Jon Kyl AZ 100 63 +37 Patrick J. Toomey PA 91 54 +37 Ron Johnson WI 91 55 +36 Thom Tillis NC 95 61 +34 Richard Burr NC 93 60 +34 David Perdue GA 95 63 +32 Johnny Isakson GA 94 63 +31 Susan M. Collins ME 79 48 +31 John Cornyn TX 96 71 +26 Rob Portman OH 94 69 +25 Jeff Flake AZ 84 60 +25 Cindy Hyde-Smith MS 100 79 +21 Ted Cruz TX 91 71 +21 Joni Ernst IA 91 71 +20 Chuck Grassley IA 91 71 +20 Tim Scott SC 96 78 +18 Dan Sullivan AK 93 79 +15 Roger F. Wicker MS 96 83 +14 Orrin G. Hatch UT 96 83 +14 Roy Blunt MO 96 83 +13 Lindsey Graham SC 90 78 +12 Pat Roberts KS 96 85 +11 Todd Young IN 94 84 +10 Bill Cassidy LA 94 84 +9 Jerry Moran KS 94 85 +9 John Boozman AR 96 89 +7 Brian Schatz HI 25 19 +7 Dianne Feinstein CA 26 20 +6 Richard C. Shelby AL 95 90 +5 Benjamin L. Cardin MD 27 21 +5 Lamar Alexander TN 93 88 +5 John Kennedy LA 89 84 +4 Mitch McConnell KY 95 90 +4 John Thune SD 95 91 +4 Lisa Murkowski AK 83 79 +4 Deb Fischer NE 92 88 +4 Mazie K. Hirono HI 23 19 +4 John Hoeven ND 96 92 +4 Patrick J. Leahy VT 25 21 +4 Steve Daines MT 89 85 +4 Tom Cotton AR 92 89 +3 Shelley Moore Capito WV 96 93 +3 James M. Inhofe OK 95 92 +3 Mike Rounds SD 92 91 +2 Thomas R. Carper DE 35 34 +2 Charles E. Schumer NY 25 24 +2 Chris Van Hollen MD 23 22 +1 Mike Crapo ID 92 91 +1 John Barrasso WY 94 93 0 Mark R. Warner VA 43 43 0 James E. Risch ID 91 91 0 Christopher A. Coons DE 33 34 -1 Tammy Duckworth IL 26 27 -1 James Lankford OK 91 92 -1 Ben Sasse NE 87 89 -1 Mike Lee UT 81 83 -2 Angus S. King Jr. (Ind.) ME 46 48 -2 Michael B. Enzi WY 91 93 -2 Jack Reed RI 27 29 -3 Richard J. Durbin IL 23 27 -4 Sheldon Whitehouse RI 25 29 -4 Maria Cantwell WA 25 29 -4 Bob Corker TN 84 88 -4 Kamala D. Harris CA 15 20 -5 Patty Murray WA 24 29 -5 Christopher Murphy CT 26 31 -5 Robert Menendez NJ 23 29 -5 Edward J. Markey MA 13 21 -8 Tim Kaine VA 34 43 -9 Bernard Sanders (Ind.) VT 11 21 -10 Richard Blumenthal CT 21 31 -10 Elizabeth Warren MA 10 21 -11 Martin Heinrich NM 27 38 -11 Tom Udall NM 25 38 -13 Bill Nelson FL 42 56 -14 Kirsten E. Gillibrand NY 9 24 -15 Michael F. Bennet CO 29 44 -15 Rand Paul KY 75 90 -15 Catherine Cortez Masto NV 33 49 -16 Ron Wyden OR 17 34 -18 Cory A. Booker NJ 13 31 -18 Jeanne Shaheen NH 35 53 -18 Margaret Wood Hassan NH 33 53 -20 Amy Klobuchar MN 30 50 -20 Tina Smith MN 27 49 -22 Gary C. Peters MI 32 54 -22 Debbie Stabenow MI 32 54 -22 Jeff Merkley OR 10 34 -24 Robert P. Casey Jr. PA 30 55 -25 Joe Donnelly IN 54 84 -30 Tammy Baldwin WI 23 55 -32 Joe Manchin III WV 61 93 -32 Doug Jones AL 50 88 -38 Heidi Heitkamp ND 54 92 -38 Claire McCaskill MO 45 83 -38 Sherrod Brown OH 28 69 -41 Jon Tester MT 37 85 -48 * Predicted scores are how often a member is expected to support the president’s position based on Trump’s vote 2016 margin in the member’s state.

Being a Republican in a blue state who almost always backs Trump and GOP initiatives is politically dangerous. Nevada’s Dean Heller, who was the last Congress’s second-most pro-Trump senator compared to his state’s politics, can attest to that — he just lost his re-election race.

McSally, who ran for a Senate seat in Arizona this fall but narrowly lost to Democrat Kyrsten Sinema, is not even in the Senate right now. But Sen. Jon Kyl, who was appointed to fill John McCain’s old seat, doesn’t have to stay in the role through 2020, when a special election will be held for the seat. Some Republicans are floating the idea of Kyl resigning so that Arizona Gov. Doug Ducey can tap McSally to fill the seat. If McSally were appointed, she would have a chance to gain some experience and build up her profile, which might make it easier for her to win the special election.

At the same time, Arizona is moving left, as McSally’s recent loss illustrates. If McSally were in the Senate in 2019 and 2020, she would likely need to distance herself from the president in some ways too.

So Collins-Gardner-Murkowski-Romney (and maybe McSally) is the coalition I’m watching in 2019.

To be clear, I don’t think this group will actually stop much of what Trump tries to do. Romney might be the next Jeff Flake, annoying conservatives by occasionally slamming Trump’s rhetoric but disappointing liberals by not actually opposing the president’s agenda much. Romney, like Flake, is fairly conservative on policy issues — I assume he would have voted yes on Brett Kavanaugh’s confirmation, for example, just as Flake did. And remember, much of the Trump agenda in the Senate is really the McConnell agenda — basically traditional Republican orthodoxy.

So where could this group play a more pivotal role? When and if Trump tries to go beyond picking traditionally conservative figures — Kavanaugh is mainstream enough that a president Jeb Bush or Marco Rubio might have selected him, too — and starts nominating true Trump loyalists or more controversial figures.

For example, some conservatives are pushing for Trump to nominate outgoing Kansas Secretary of State Kris Kobach to run the Department of Homeland Security. The president seems ready to remove current DHS Secretary Kirstjen Nielsen, and Kobach and Trump are aligned on pushing U.S. policy toward greater limits on immigration. But I’m not sure Gardner or Romney will want to vote for Kobach.

Also, beyond votes, I think these senators are likely to be the Republicans in Washington who are most willing to criticize Trump publicly. And, as I have written before, there is some evidence that such criticism from within his own party matters to the president. Key Republicans in the Senate, for example, strongly urged Trump to reverse his policy that resulted in children being separated from their families at the border, which he eventually did.

“I expect that the unusually stark Senate Republican criticism of the president will continue on issues like Russia and foreign policy,” said Matt Glassman, a congressional expert at Georgetown University’s Government Affairs Institute. “And I believe that has a serious effect of constraining Trump.”

Glassman thought Romney in particular could play a major role the next two years.

“He’s going to be very conservative, but also very loud at times,” Glassman said. “He likes and wants the stage.”