Republicans across the most competitive House and Senate races have settled on a closing pitch ahead of Election Day: Democrats are too extreme to be given control of Congress. It is an effort, pressed in a flood of TV ads and in President Trump’s rally speeches, to urge voters who are angry about gas prices and broader economic conditions to redirect their frustration away from the party in power. To make their case, Republicans are calling renewed attention to a set of cultural issues that hurt the Democratic Party in 2024, among them transgender athletes in women’s sports, border security and the claim that Democrats want socialism.

Democrats are trying to blunt the attack by siding with Trump and his party on some of these issues over progressives who first propelled the ideas. An SLF PAC ad against Democratic Senate candidate Sherrod Brown. — SLF PAC“There is no question that crossings are way down, and there is no question it is because of President Trump,” Gina Hinojosa, the Democratic nominee for governor in Texas, said of illegal immigration in a TV interview.“I don’t support biological men playing women’s sports,” says Annie Andrews, the Democratic Senate candidate in South Carolina, in a direct-to-camera TV ad.“No way do we defund the police,” says Roy Cooper, the Democrats’ Senate nominee in North Carolina, in an ad.

“You deserve to feel safe, and there’s nothing political about that.”In casting Democrats as out of the mainstream, Republicans are trying to appeal to their voters’ partisan impulses as polls find that many are unmotivated to vote.

They also worry that GOP Senate candidates, such as Ken Paxton in Texas and Roger Marshall in Kansas, are drawing lower levels of support than are the party’s gubernatorial candidates. That suggests that some Republicans are backing the Democrat in those Senate races, might skip voting for senator or sit out the election altogether.

Democrats have similar problems with their Senate candidates in states such as Michigan.“You can vote for the radical left Dumocrat communists to loot your wealth, raise your taxes by $5 trillion, annihilate your borders,” Trump said at a rally this week in Ohio, in what has become a familiar element of his recent campaign speeches. By contrast, he said, “You can defeat the Dumocrat communists and vote for more money in your pockets…If you want that, you must vote Republican.”‘God is nonbinary’Republicans in some states have leaned heavily on claims that their opponents are out of step with voters by favoring transgender rights.

In Ohio, Trump criticized the Democrats’ Senate nominee, Sherrod Brown, saying: “He wants to see men playing in women’s sports. He wants to see transgender mutilation of your children.”Brown has said he opposes transgender women in girls’ sports, and that the question of transgender care for minors is settled law. “In Ohio, it’s against the law to perform transgender surgeries on kids,” one of his TV ads says.

“That’s right, it’s illegal.”An from Friends of Sherrod Brown. — Friends of Sherrod Brown“I do see far more headlines of my opponent talking about trans issues than the things I hear about across the district,” said Bale Dalton, the Democratic House nominee in a Florida district.

He ticked off the cost of living, healthcare costs and the war in Iran as issues he hears most from voters. Just since Sept. 1, a Republican super PAC has spent $59 million on three ads attacking James Talarico, the Democratic nominee for Senate in Texas, for allegedly backing gender transition care for minors, ranking those ads in the top five across all House and Senate races for the amount of money spent airing them.A fourth ad, backed by more than $10 million in spending in the past six weeks, reprises Talarico’s statements that “there are many more than two biological sexes” and that “God is nonbinary.”

It ends with the statement, “James Talarico: For they/them, not for you”—reprising a line that Trump used effectively against his Democratic opponent in 2024.

Talarico says he supports a national ban on gender-affirming surgeries for minors but believes parents and doctors should determine other care. Appearing on CNN this week, he said that God can’t be defined using human categories, so that his comment about a nonbinary deity was theologically uncontroversial.A MAGA Inc. ad against Democrat James Talarico, a Senate nominee in Texas. — MAGA Inc.A Talarico for Texas Senate . — Talarico for Texas SenateMany other Democrats in competitive races have sought to distance themselves from the debates over trans rights that were prominent several years ago.

Rob Sand, running for governor in Iowa, as well as gubernatorial candidate Amy Acton in Ohio and Rep. Don Davis in North Carolina, have all said that their states have regulated transgender participation in sports or gender-affirming care for minors, and so the matter is settled law.

Blunting Democratic enthusiasmIn addition to Trump, other GOP leaders are trying to portray Democrats as outside the mainstream, sometimes drawing on statements from Democratic socialists.

“The Democrats are running candidates who say we need to destroy the American way of life and want to destroy the nuclear family,” Vice President JD Vance said last month in Iowa, adding: “Some of the Democrats running this fall, they are out-and-out lunatics.”In Florida, GOP Rep. Maria Elvira Salazar shows images of New York Mayor Zohran Mamdani, Sen. Bernie Sanders (I., Vt.) and other Democratic socialists in a recent ad attacking Eliott Rodriguez, her Democratic challenger. The ad says Rodriguez supports Democrats who are bent on “replacing our free market with a socialist economy.”

Rodriguez, in an interview, called himself a product of the free enterprise system and said his father, a Cuban immigrant, was a businessman who ran a bodega in the Bronx. “I denounce socialism,” Rodriguez said. He added that Salazar and other Republicans were trying to portray Democrats as extreme “because they have no answers to the questions voters are asking, which are, ‘What are you going to do about this economy and the cost of living?’ ”One factor helping the GOP effort: Voters in battleground districts have a worse opinion of the Democratic Party than the GOP, some polling shows, suggesting that voters in the most competitive races might be receptive to the Republican claims.

“For that reason, finishing with an argument that says ‘Don’t give the other side the keys to Congress’ is our best option,” said GOP pollster Wes Anderson. “Whether that’s going to be enough to blunt Democratic enthusiasm remains to be seen.”In 2010, with the nation still smarting from a financial crisis, then-President Barack Obama urged voters to stick with his party in midterm elections, rather than return the keys to a Republican Party that he said had driven the national car into a ditch. His party wound up losing 63 House seats that year.

Some analysts say that shows it’s hard to persuade voters to look back in time when they make their voting choices rather than react to current conditions.“I’m in 22 congressional races and several Senate races, and in every competitive race the Democratic message is about costs and corruption, and the Republican message is about trans and socialism,” said Chuck Rocha, a Democratic strategist.

He said he thinks it is unlikely the GOP pitch works this year, though he can’t rule it out.“The social and cultural stuff only works when everyone’s belly is full and gas is $2 a gallon,” he said. “It works at times, and this ain’t one of them. But there’s always a chance. I said Donald Trump would never be elected, and he won two times.”

Write to Aaron Zitner at aaron.zitner@wsj.com and Neil Mehta at neil.mehta@wsj.com