Rep. Ileana Ros-Lehtinen (R-Fla.), pictured on March 16, has announced that she won’t seek reelection. (Matt McClain/The Washington Post)

One of the most influential Cuban Americans in Congress announced that she will retire next year rather than seek reelection in an evolving South Florida district that once helped launch prominent Florida Republicans but is now moving toward Democrats.

Rep. Ileana Ros-Lehtinen (R), the first Hispanic woman and the first Cuban American elected to Congress, will end a 30-year run on Capitol Hill next year as one of her party’s leading moderate voices on social issues. She will leave behind a district that President Trump lost by 20 percentage points, the most Democratic-leaning district held by a Republican based on last year’s presidential contest.

Part of her party’s wing that opposed Trump’s candidacy, even during the general election, Ros-Lehtinen told the Miami Herald that she was not retiring because of her differences with Trump or her prospects of a difficult reelection bid. Instead, she said it was the right time after nearly four decades in local and federal office.

“It’s been such a delight and a high honor to serve our community for so many years and help constituents every day of the week,” she told the Herald on Sunday. “We just said, ‘It’s time to take a new step.’ ”

She burst onto the scene in 1988 with her first congressional victory, heralding the power of Cuban émigrés and their children in South Florida’s politics. For years now, three House districts in South Florida have been held by Cuban Americans, almost all Republicans. They have formed a vocal opposition to the Castro regime in Cuba and also delivered votes for GOP candidates who also pledged to fight the dictator.

Her first campaign manager, a young Jeb Bush, launched a new flank of the family political dynasty from that part of Florida, becoming governor and then basing his 2016 presidential campaign in that region. Ros-Lehtinen was a staunch Bush supporter, only to see his bid to become the third Bush to win the presidency fail amid a relentless assault of personal insults from Trump during the Republican primary contest.

Democrats pounced on the news of Ros-Lehtinen’s retirement, rejecting her denials that it had anything to do with Trump or the floundering legislative effort during the first 100 days of his presidency and unified GOP control of Congress.

“This is first of many retirements,” Meredith Kelly, spokeswoman for the Democratic Congressional Campaign Committee (DCCC), predicted on Twitter. Kelly said that many Republicans will not want to defend the “embarrassment of GOP DC” and will instead choose to retire.

“Starting earlier than expected,” Kelly said of Ros-Lehtinen’s decision.

Although she was a staunch conservative on most foreign policy matters, Ros-Lehtinen steered clear of the party’s increasingly conservative views on social matters, particularly gay rights. In recent years, her son, Rodrigo Lehtinen, who is transgender, took on a prominent role among Florida’s gay rights community.

The Miami-based district, which includes South Beach and Key Biscayne, has increasingly turned away from national Republican politics, particularly as the more recent generations of Cuban Americans expanded their political viewpoints beyond policy toward Cuba.

Florida’s 27th Congressional District voted for Sen. John McCain (R-Ariz.) in the 2008 presidential election, 51 percent to 49 percent, but four years later, Ros-Lehtinen’s district supported President Barack Obama, 53 percent to 47 percent, over Republican Mitt Romney.

Then Trump’s nationalist campaign, with rhetoric that liberal Latino activists used to increase turnout, turned the district solidly blue: Democrat Hillary Clinton won there by 19.7 percentage points.

Despite Trump, Ros-Lehtinen remained popular in South Florida. She won reelection last year by almost 10 percentage points, and she would have been a formidable opponent in 2018. Still, last year marked a more difficult campaign than her usual previous victories of more than 20 percentage points, and she was going to need to raise millions of dollars to fight again next year.

“There was no epiphany. There was no moment, nothing that has happened that I’ve said, “I’ve got to move on,’ ” said Ros-Lehtinen, 64.

Three Democrats had already declared for the 2018 contest, but the DCCC’s recruiting range may now expand because it will be an open seat rather than a challenge against a well-known institution of Florida politics.