The announcement from Sen. Roy Blunt (R-Mo.) that he won’t seek reelection does more than create another open seat. It shows that the GOP’s old guard is fast departing, leaving the party’s future very much up for grabs.

Blunt is the fifth Republican senator to declare he won’t run again, and he’s likely not the last. Sen. Ron Johnson of Wisconsin recently said that not running “is probably my preference now,” and 87-year-old Charles E. Grassley of Iowa has said he’ll decide whether to run for his eighth term in the fall. Two other Republicans up for reelection, Sens. Mike Crapo of Idaho and John Neely Kennedy of Louisiana, would be 71 years old in 2022 and have not yet declared their intentions. At the current rate, no one should be surprised if one or more of these men decide it’s time to leave.

These decisions will affect the outcome of the midterm elections, as at least two of the retiring senators, Pennsylvania’s Patrick J. Toomey and North Carolina’s Richard Burr, represent classic swing states. Johnson’s Wisconsin is another partisan battleground that will be tightly contested no matter what he decides. The other retirements from safely Republican states, however, are also likely to be politically important. Each of the retirees is a classic establishment conservative more likely to back Senate Minority Leader Mitch McConnell (R-Ky.) than former president Donald Trump. Their replacements might have the opposite inclination.

Alabama’s Senate seat is a case in point. Sen. Richard C. Shelby was a conservative Democrat before switching parties after the 1994 Republican landslide. The only declared candidate to replace him to date is Lynda Blanchard, a wealthy GOP donor whom Trump appointed as ambassador to former first lady Melania’s home country of Slovenia. Blanchard is running as a Trump-like conservative outsider, going so far in her opening video as to drive a truck with a “Trump-Pence 2020” sticker on the rear windshield. She has already deposited $5 million in her campaign account, enough to show she’s serious about the race.

Other potential contenders are also strong conservatives, albeit perhaps less clearly tied to Trump. Rep. Mo Brooks of Alabama, a leader in the drive to challenge President Biden’s election on Jan. 6, has said he’s considering joining the race, as has Alabama Secretary of State John Merrill. Both would campaign as conservatives, with Brooks likely playing up his role in challenging the 2020 election to prove his pro-Trump bona fides.

Perhaps the most obvious potential establishment candidate is Katie Boyd Britt, former Shelby chief of staff and the current chief executive of the Business Council of Alabama. Only 38 years old, Britt has not served in elected office, but her longtime association with Shelby and her current job give her access to donors and activists. If she runs, however, she would surely need to echo many of the conservative cultural themes so prevalent in today’s GOP to prevail. That’s what Atlanta business executive Kelly Loeffler had to do in her race to remain Georgia senator, running an ad claiming she is “more conservative than Attila the Hun” to make her case.

The race to succeed Sen. Rob Portman of Ohio is also shaping up to be a competition to see who is closer to Trump. Former state treasurer Josh Mandel ran for the Senate against Democrat Sherrod Brown in 2012 as a standard conservative. Today, he’s running as a pro-Trump acolyte who’s running to “pulverize the uniparty” of “Democrats and Republicans who sound exactly the same.” His main competition so far is former state GOP chair Jane Timken, a Trump-friendly candidate who won her post after unseating a loyalist to anti-Trump former governor John Kasich. Timken is endorsed by former Trump staffers Stephen K. Bannon and Peter Navarro and proclaimed fealty to Trump’s “America First agenda” in her announcement video. Both Mandel and Timken are likely to be more voluble and populist than the retiring Portman, who served in George W. Bush’s administration and lamented the decline of bipartisanship in his retirement announcement.

These departures mean that almost the entire GOP Senate caucus will be composed of people elected after the tea party helped create the GOP’s current populist nature. Amy Walter of the Cook Political Report notes that after 2022, only 22 percent of the caucus will have been elected before 2010. That number would decline further if Grassley or Crapo choses to retire. Virtually all of these recently elected members are either hard conservatives or part of the GOP’s reformist wing, or both.

The GOP’s future depends on channeling the current populist, Trumpian elements into a vessel that is also welcoming to the educated, suburban White people who left the party to support Biden. The races to fill safe Senate seats such as Blunt’s will be the first indicator whether the party can find that sweet spot.

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