President Trump's vow to end birthright citizenship caused heartburn for Republican candidates across the country and could endanger the GOP in key races with suburban voters or high immigrant populations.

For Republicans who find themselves in tight races with little time to persuade swing voters, their focus with just a week to Election Day is to hone their campaign message. That's not going to happen with Trump. Instead, the president seems intent on inserting himself as the deciding factor in the midterm elections.

Rep. Carlos Curbelo, R-Fla., fighting to cling on to his seat, took the hardest stance against the president. "Birthright citizenship is protected by the Constitution, so no @realDonaldTrump you can’t end it by executive order,” Curbelo tweeted. “What we really need is broad immigration reform that makes our country more secure and reaffirms our wonderful tradition as a nation of immigrants."

Florida Gov. Rick Scott, in a nail-biting Senate race against Sen. Bill Nelson, D-Fla., avoided taking questions from reporters Tuesday morning at a press conference, later sending out an anodyne campaign statement: "I have not seen the details of what the president is suggesting and would need to fully review the proposal. My priorities continue to be securing the border and fixing the long-broken immigration system."

In just three sentences Monday, Trump sparked a nationwide controversy with comments that he has already started the process of striking birthright citizenship from the 14th Amendment.

"It’s in the process. It’ll happen, with an executive order ... We’re the only country in the world where a person comes in and has a baby, and the baby is essentially a citizen of the United States,” Trump told Axios Monday. “It’s ridiculous. It’s ridiculous. And it has to end."

But while the president's comments sent Washington and the media scrambling, some Republican strategists are less concerned, although they realize that any event or gaffe — major or minor — can have potential implications in the final week before an election.

"We are officially in crazy time. Crazy time is that period the week or two before the election where every mole hill becomes a mountain. Every new survey is the end of times where the election swings in a different direction every day," Alex Castellanos, a GOP strategist, told the Washington Examiner. "Is this is the decisive issue that tips the scales one way or another? This is not."

A number of strategists raised the point that the president has an accurate pulse of his base. Since midterm elections are "base" elections and Republican voters list immigration among their top campaign issues, the president could be making a savvy political maneuver.

"Trump has the best political instincts of any predator in the political jungle. When he sees raw meat, he eats it. And it usually turns out to be that his political instincts were right. That may be the case here," Castellanos said.

Republicans, on a national basis, favor of ending birthright citizenship by a slim majority, according to a September 2017 Wall Street Journal/NBC News poll. Some 52 percent of Republicans favored ending birthright citizenship, compared to 48 percent that reported being against it.

Even though a narrow majority of Republican voters support the move, there are still reasons to be concerned. The president is firing up his base, which is valuable because midterm elections hinge on voter turnout, but he is also potentially alienating a block of voters that came out for him in 2016. The president took 49 percent of the suburban vote, besting former Secretary of State Hillary Clinton among that voting block by 4 percentage points. Those voters, strategists argue, could sway against the president over birthright citizenship.

"In Arizona and Nevada, you have a lot of suburban voters, and they like what Trump is doing so far, but he has to pump the brake pedal. In those states, this doesn’t play well. In those states, they feel he wants to stop us from being Americans," Castellanos said. "I haven’t talk to a Republican consultant yet that doesn’t say, 'I wish he had held this till after the election.' Does it fire up his base? Yes. Does his base need firing up? Continually."

"I think he has energized Hispanics who weren’t necessary that energized against him. Even Hispanics don’t like illegal immigration, but when you get to voters, they’d like to see a way to do this that respects the process. This is almost a bridge too far in some ways for Hispanic votes," Castellanos said, adding that it does not hurt his "base."

In addition to Arizona and Nevada, Trump's statement is most likely to put Republican candidates in states with high immigrant populations, like Texas and Florida, in a tough position.

In Texas, whose population overwhelmingly supported ending birthright citizenship during the 2016 Republican primary, Republicans aren't as likely to feel the impact.

The University of Texas and the Texas Tribune found that 66 percent of Texas Republicans support repealing birthright citizenship from the 14th Amendment. Sen. Ted Cruz, R-Texas, who currently finds himself in a highly-watched race against Rep. Beto O'Rourke, D-Texas, has supported and continues to support ending birthright citizenship as a mechanism for curbing illegal immigration.

Candidates running in Florida are having a more difficult time. The state's immigrant population, particularly those from Cuba and Puerto Rico, keeps the immigration debate at the forefront of every election cycle. A CBS/YouGov poll published Sunday found 91 percent of Floridian respondents listed immigration as "very important" or "somewhat important" in their voting calculus this cycle. GOP candidates in the state are either tacitly supporting the president or are supporting him with the caveat that it will like be challenged in the courts.

Florida GOP gubernatorial candidate Rep. Ron DeSantis is taking a different approach, lauding the president's move but cautioning that it will likely face a number of court challenges if he decides to move forward.

"As a matter of policy, I don’t think the Constitution intended that people could come illegally in order to get citizenship,” DeSantis told the Tampa Bay Times. “That being said, there has been a long list of out [sic] decisions that I think you’d have to reckon with."

In the end, strategists believe that this election will come down to whether or not Trump allows this election to be about the issues, or about himself. If he chooses the former, like he did in 2016, Republicans should win. If he makes it about himself, which he has thus far, it will not go in the Republicans' favor.

"If this election is about Kavananugh, the caravan and America becoming more chaotic, uncertain and out of control, then Donald Trump is the brake pedal that Americans can tap to keep our country from going farther run the wrong direction," Castellanos said. "Republicans will win in that scenario."

"If this election is about Donald Trump going too far, then voters will tap the brake pedal to protect the country from that. What Trump is doing at the very tail end, which he didn’t do in 2016, is making [the election] about him and not Washington," Castellanos said. In this scenario, Castellanos said the election likely goes for Democrats.