More and more top Republicans are warning that Trump's groundless claims about mail-in voting could tank the party in November

• Kevin McCarthy, the Republican Party's top House lawmaker, has told Axios that President Donald Trump's war on mail-in voting could backfire.
• "We could lose based on that," McCarthy told the outlet, and said he had personally addressed the issue with Trump.
• McCarthy believes that older voters — a key part of the GOP's support — worried about catching the coronavirus could be deterred by Trump's attacks from voting by mail.
• He is one of multiple top Republicans to break with the president over the issue, with several GOP senators having also backed mail-in voting.

House Minority Leader Kevin McCarthy has joined the list of GOP lawmakers concerned that President Donald Trump's groundless attacks on mail-in voting could could cost the party in November's presidential election.

In an interview with Axios published Sunday, McCarthy said he was privately encouraging voting by mail, and believes that the party could be "screwed" by the president's attacks on the integrity of the process.

"We could lose based on that," McCarthy told the outlet, adding that he has personally addressed the issue with Trump.

"I tried to show him ... you know who is most afraid of COVID? Seniors. And if they're not going to go vote, period, we're screwed," McCarthy told Axios.

McCarthy's comments echo growing concern among some Republicans that Trump's hostility to mail-in voting could backfire.

Millions more Americans are expected to cast their ballots by post this year amid ongoing concern about the coronavirus, and the method is particularly popular among older and rural voters, who tend to support the Republican Party.

The president has claimed, contrary to the assurances of election officials and experts, that the process is exposed to widespread fraud.

He has even encouraged supporters to vote twice to test the integrity of the system — a move that is in violation of election laws.

Some Republicans believe that a surge in mail-in votes would benefit Democrats, with Democratic presidential candidate Joe Biden currently leading Trump in national polls, and by a narrower margin in a Fox News survey of swing state polls.

But FiveThirtyEight, citing a number of studies, reported in May that there is little evidence that mail-in voting confers an advantage on either party.

Some Republican senators have broken with the president over mail-in ballots in recent weeks, with the party's second-highest ranking member of the Senate, John Thune of South Dakota, telling reporters in August he didn't accept that the process was more exposed to fraud or gave an advantage to Democrats.

"It's always a war too for mail-in ballots. Both sides compete, and it's always an area where I think our side, at least in my experience, has done pretty well," Thune said, as quoted by Fox News.

"I think we want to assure people it's going to work, it's secure and if they vote that way it's going to count," he added, according to the network.

Sens. Rob Portman of Ohio, Rick Scott of Florida, and Mitt Romney of Utah have all also expressed support for the integrity of the mail-in voting system.

In some states the GOP is quietly encouraging voters to cast their ballot by mail, Politico reported, amid concern from some party officials that Trump's attempts to cast doubt on the process could put off supporters who want to cast their ballot remotely.

The party officials are reportedly concerned about polls showing that more Democrat voters are signing up to vote by mail than Republicans in some swing states.

The president has sought to draw a distinction between absentee voting — where voters request a mail ballot — and mail-in voting, where registered voters are sent one automatically, claiming that absentee ballots are not exposed to fraud.

The Brookings Institute think tank has found no evidence that either process is particularly exposed to fraud.

• Read more:
• Why you should request your November mail ballot as soon as possible, and when you can expect to receive it
• Facebook says it will remove videos of Trump encouraging people to vote twice, unless they're being posted to show he's wrong
• 5 mistakes that can disqualify your November mail ballot and how to avoid them