Three Republican committee chairmen sought to use their investigative power to involve themselves in the Manhattan district attorney’s criminal inquiry into the former president.ORLANDO, Fla. — House Republicans rallied around former President Donald J. Trump on Monday ahead of his expected indictment by a Manhattan grand jury, using their investigative power to scrutinize active criminal inquiries targeting him as at least one other G.O.P. lawmaker endorsed his 2024 presidential campaign.Three Republican committee chairmen demanded on Monday morning that Alvin Bragg, the Manhattan district attorney who is said to be close to indicting Mr. Trump, provide communications, documents and testimony about his investigation, an extraordinary move by Congress to involve itself in an active criminal inquiry.“You are reportedly about to engage in an unprecedented abuse of prosecutorial authority.” wrote Representatives Jim Jordan of Ohio of the Judiciary Committee, James R. Comer of Kentucky of the Oversight and Accountability Committee and Bryan Steil of Wisconsin of the Administration Committee. “If these reports are accurate, your actions will erode the confidence in the evenhanded application of justice and unalterably interfere in the course of the 2024 presidential election.”They demanded “all documents and communications referring or relating to the New York County District Attorney Office’s receipt and use of federal funds.”That office receives very little funding from the federal government, according to its most recent budget, but the letter also served as a warning to the F.B.I. and the Justice Department, which is also considering prosecutions of Mr. Trump.The letter was House Republicans’ latest effort to use their investigatory powers to defend Mr. Trump. They have authorized a new subcommittee to scrutinize criminal investigations into Mr. Trump’s conduct and quietly wound down a congressional inquiry into his finances and conflicts of interest as president.The Justice Department has so far resisted what federal prosecutors view as unnecessary intrusions into their work, citing longstanding department policy. Mr. Bragg was anticipated to be unlikely to allow Republicans access to materials related to an active case.“We will not be intimidated by attempts to undermine the justice process,” Danielle Filson, a spokeswoman for Mr. Bragg’s office, said on Monday, adding: “In every prosecution, we follow the law without fear or favor to uncover the truth. Our skilled, honest and dedicated lawyers remain hard at work.”Still, Mr. Trump’s lawyers have quietly urged the Republican-led House to interfere. Last month, Mr. Trump’s lawyer Joseph Tacopina wrote to Mr. Jordan calling on Congress to investigate the “egregious abuse of power” by what he called a “rogue local district attorney,” according to a copy of the letter obtained by The New York Times.But Representative Jamie Raskin of Maryland, the top Democrat on the Oversight and Accountability Committee, said it was Republicans who were abusing their power. “These committee chairs have acted totally outside their proper powers to try to influence a pending criminal investigation at the state level,” he said in a statement.The news of the Republicans’ letter came as House G.O.P. lawmakers, who have gathered for a retreat in Orlando to plot out their policy agenda, were facing fresh political calculations about how to position themselves as Mr. Trump confronts new challenges and a potentially divisive presidential primary looms.Representative Anna Paulina Luna of Florida, who has been loyal to both Mr. Trump and Gov. Ron DeSantis of Florida, announced her official endorsement of Mr. Trump’s presidential campaign on Monday, indicating that the expected indictment had pushed her to unequivocally choose sides.“I support President Trump,” Ms. Luna said in a statement to The New York Times. In explaining her support, she said that Mr. Bragg was “trying to cook up charges outside of the statute of limitation against Trump” and that “this is unheard-of, and Americans should see it for what it is: an abuse of power and fascist overreach of the justice system.”.css-1v2n82w{max-width:600px;width:calc(100% – 40px);margin-top:20px;margin-bottom:25px;height:auto;margin-left:auto;margin-right:auto;font-family:nyt-franklin;color:var(–color-content-secondary,#363636);}@media only screen and (max-width:480px){.css-1v2n82w{margin-left:20px;margin-right:20px;}}@media only screen and (min-width:1024px){.css-1v2n82w{width:600px;}}.css-161d8zr{width:40px;margin-bottom:18px;text-align:left;margin-left:0;color:var(–color-content-primary,#121212);border:1px solid var(–color-content-primary,#121212);}@media only screen and (max-width:480px){.css-161d8zr{width:30px;margin-bottom:15px;}}.css-tjtq43{line-height:25px;}@media only screen and (max-width:480px){.css-tjtq43{line-height:24px;}}.css-x1k33h{font-family:nyt-cheltenham;font-size:19px;font-weight:700;line-height:25px;}.css-1hvpcve{font-size:17px;font-weight:300;line-height:25px;}.css-1hvpcve em{font-style:italic;}.css-1hvpcve strong{font-weight:bold;}.css-1hvpcve a{font-weight:500;color:var(–color-content-secondary,#363636);}.css-1c013uz{margin-top:18px;margin-bottom:22px;}@media only screen and (max-width:480px){.css-1c013uz{font-size:14px;margin-top:15px;margin-bottom:20px;}}.css-1c013uz a{color:var(–color-signal-editorial,#326891);-webkit-text-decoration:underline;text-decoration:underline;font-weight:500;font-size:16px;}@media only screen and (max-width:480px){.css-1c013uz a{font-size:13px;}}.css-1c013uz a:hover{-webkit-text-decoration:none;text-decoration:none;}How Times reporters cover politics. We rely on our journalists to be independent observers. So while Times staff members may vote, they are not allowed to endorse or campaign for candidates or political causes. This includes participating in marches or rallies in support of a movement or giving money to, or raising money for, any political candidate or election cause.Learn more about our process.Ms. Luna indicated to Politico last week that she would lean toward Mr. Trump in a presidential matchup against Mr. DeSantis. But her full-throated endorsement underscored the forces pulling at Republicans as Mr. Trump riles up his base to support him in what he is framing as a politically motivated indictment.Mr. Trump, until now, has been more ignored than embraced by House Republicans who have preferred not to choose sides in the still-developing 2024 presidential primary.Ms. Luna, 33, was elected in November after being endorsed by both Mr. Trump and Mr. DeSantis, who also campaigned with her in the general election and called her a “principled fighter.” In the past, while trying to stay out of the brewing dogfight between the two Republican leaders, she has noted that “it’s not uncommon now to see Trump-DeSantis 2024 flags.”But with Mr. Trump claiming he would be arrested on Tuesday and agitating for people to “protest,” and Republican leaders rushing to defend him, Ms. Luna came off the sidelines.“I’m sick of the press trying to create an enemy out of someone who actually had our country in a good place from an economic and policy perspective,” she said. “Save me the virtue signaling. Trump 2024.”At the retreat here on Monday, Republicans across the board denounced Mr. Bragg and defended Mr. Trump.Representative Mario Díaz-Balart of Florida said on Monday that Mr. Bragg was a “rogue, left-wing, radical prosecutor who now has decided for political reasons to go after a former president.” He said he condoned peaceful protests in response and added of the expected indictment: “We’re used to seeing that in third-world countries. That’s something that doesn’t happen in this country.”Speaker Kevin McCarthy of California also said on Sunday that Mr. Bragg was politically motivated but argued against protests. “It’s interesting to me that he spent his whole time as a D.A. lowering felonies not to prosecute,” Mr. McCarthy said of Mr. Bragg. “Republicans and Democrats alike hate this kind of justice.” (Ms. Filson said homicides and shootings had declined under Mr. Bragg.)In an interview, Representative Elise Stefanik of New York, one of Mr. Trump’s most fervent defenders and the only party leader to endorse him, said the expected indictment “only strengthens President Trump moving forward.” And she did not discourage people from protesting, as he has urged them to do. “I do believe people have a constitutional right of freedom of speech to speak up when they disagree,” she said.Ms. Luna, a member of the House Freedom Caucus, was one of the few freshman lawmakers to join a group of rebels who voted against Mr. McCarthy during his protracted fight to win the gavel in January. She did not attend the retreat in her home state.But in a lengthy statement, Ms. Luna accused President Biden of overseeing a “botched withdrawal from Afghanistan” and pursuing a “soft-on-China approach” and charged that his family corruptly profited from the Chinese government. “And yet people are clutching their pearls and still parroting the ‘orange man bad’ mentality?” she said.Most House Republicans have remained neutral in the 2024 presidential race. Last week, Representative Chip Roy of Texas pre-emptively endorsed Mr. DeSantis, even though he has yet to officially start a presidential campaign. And Representative Ralph Norman, Republican of South Carolina, endorsed Nikki Haley, the state’s former governor.A handful of Trump loyalists, including Ms. Stefanik and Representative Marjorie Taylor Greene of Georgia, have endorsed the former president. But most have seen little benefit to expressing a preference in the race at this early stage.That decision has been that much harder for members of the Florida delegation — until the expected indictment prompted at least one of them to intensify their defense of Mr. Trump.“DeSantis is a great leader for Florida,” Ms. Luna said, “and I will continue to support him as my governor.”Annie Karni More