Rep. Mo Brooks of Alabama showcased his support and loyalty for former President Donald Trump as he launched his Senate campaign.

To hammer home the point, he was accompanied by Stephen Miller, a top adviser to Trump during his tenure in the White House and the architect of the administration's hard line on illegal immigration. Miller, who endorsed the congressman's Senate bid, stressed that "nobody over the last four years has had President's Trump's back more than Mo Brooks."

BROOKS SPOTLIGHTS SUPPORT FOR TRUMP AS HE LAUNCHES SENATE BID

And in an exclusive national interview with Fox News, the congressman spotlighted his "very good relationship" with Trump, emphasizing that "I have stood by his side during two impeachment hoaxes, during the Russian collusion hoax, and in the fight for honest and accurate elections. The president knows that. The voters of Alabama know that, and they appreciate it."

About an hour before Brooks officially launched his campaign to succeed retiring longtime GOP Sen. Richard Shelby, former Missouri Gov. Eric Greitens announced his candidacy for the Senate during an appearance on Fox News' "Special Report."

Greitens told Bret Baier that the people of Missouri "need somebody who is going to go – as I will, as I am committed to do – to defending President Trump's 'American First' policies and also to protecting the people of Missouri from Joe Biden, Nancy Pelosi and Chuck Schumer's radical leftist agenda."

Greitens, who resigned in 2018 amid allegations of sexual misconduct and campaign irregularities, is seeking to succeed retiring Republican Sen. Roy Blunt.

FORMER MISSOURI GOV. GREITENS LAUNCHES CAMPAIGN FOR SENATE

Blunt and Shelby, longtime denizens of Capitol Hill, aren’t the only Republican senators who are retiring next year rather than run for reelection. Sens. Pat Toomey of Pennsylvania and Rob Portman of Ohio have also announced in the past couple of months that they would not launch reelection campaigns. Sen. Richard Burr of North Carolina said during his 2016 reelection that he wouldn't run again in 2022. Another old bull of the Senate – 87-year-old Sen. Chuck Grassley of Iowa – is also mulling retirement.

In many cases, allies of the former president are front and center in the race to replace these retiring "old guard" lawmakers.

Brooks isn't the only Republican in the Alabama race who is hoping to receive the former president’s blessing.

Alabama businesswoman Lynda Blanchard, who served as U.S. ambassador to Slovenia during the final two years of the Trump administration, is also touting her credentials as an ally of the former president.

"We will give the Swamp a heckuva dose of the common sense and conservative principle that it needs to truly 'Make America Great Again' – just like President Trump did," Blanchard vowed as she announced her candidacy last month.

In Missouri, Rep. Jason Smith, a major Trump supporter, is also considered a potential Senate contender.

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In Ohio, the two major Republican candidates to already jump into the race – former state GOP chair Jane Timken and former state treasurer and former Senate candidate Josh Mandel – have both made their support for Trump centerpieces of their campaigns.

Another major Trump supporter, Ohio businessman and 2018 Senate candidate Mike Gibbons, recently took a big step toward formally launching a campaign. And the field of pro-Trump contenders is likely to grow.

More than two months removed from the White House, Trump is still incredibly popular with Republican voters, and his clout over GOP politicians remains immense. The former president touted in a podcast Monday that his endorsement in a GOP primary "has meant the difference between a victory and a massive defeat."

GOP strategist Andrea Bozek noted that "for conservatives, President Trump has a clear record of accomplishments – when you consider the conservative judges he appointed, tax relief and his immigration policy."

"In most Republican primaries across the country I think you will see smart candidates try and tap into his popularity with conservatives," added Bozek, a former communications director for the National Republican Senatorial Campaign and the National Republican Congressional Campaign.

LONGTIME GOP SEN. RICHARD SHELBY THE LATEST OF THE SENATE OLD GUARD TO ANNOUNCE 2022 RETIREMENT

GOP primary politics in states where the former president won big in 2020 – Trump captured Mississippi by 26 points, Missouri by more than 15, and Ohio by 8 – is simple.

"It's not going to be a terribly complicated political formula in a state where President Trump remains extremely popular," longtime Republican strategist Colin Reed said. "You just wrap yourself as closely as you can around him and hope and pray that he or his network will endorse you or say nice things about you."

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Reed, a veteran of Republican presidential and Senate campaigns, said that wide open GOP Senate primaries "in the ruby red states" are not a problem for the party "so long as these Republican candidates can pass a basic vetting test."

But in battleground states – such as Pennsylvania and North Carolina, where the GOP’s defending open seats – and Arizona, Nevada and New Hampshire, where Republicans hope to flip blue seats red as they try to retake the Senate majority next year, it’s a different story.

In these swing states, Reed said "I think the Republican Party wants to find a nominee that all factions of the party can unite behind."