House Republican Leader Kevin McCarthy is privately encouraging voting by mail and warned President Trump the party could be "screwed" by his fight against mail-in voting.

The big picture: "We could lose based on that," McCarthy (R-Calif.) told me at a diner in Salt Lake City last week, during a campaign swing that began in the Pacific Northwest. McCarthy said the party can't afford for Republicans to sit home, afraid of getting COVID-19, while Democrats flood the field with mail-in ballots.

• McCarthy is particularly worried about deterring senior citizens.

McCarthy said he's spent hours telling Trump that this preoccupation will hurt the president's own re-election, as well as Republicans running for Congress.

• "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 me.

The other side: Trump trashes mail voting in part because he sees the messaging as good cover if he loses to Joe Biden in November, sources close to the president’s re-election campaign tell Axios.

• Last week, Trump even encouraged supporters in North Carolina to violate the law and vote twice — through the mail and in-person — to test the process.

The backdrop: I traveled with McCarthy last week as he campaigned and raised money for candidates in Oregon and Utah. At every stop, he told Republicans to vote by any means necessary.

• He told donors in both states the story of Republican Mike Garcia’s knockout win in May's special election for California's 25th district, the seat that former Democratic Rep. Katie Hill carried by 9 points in 2018.
• “It was a seat everyone thought was unwinnable, but we won it,” McCarthy told donors at a winery in Oregon.
• McCarthy attributed the win in part to the twist in which California Gov. Gavin Newsom, a Democrat, mandated late that all ballots be cast by mail to prevent the spread of the coronavirus, avoiding the obstacles of same-day voter registration.

Between the lines: McCarthy says he agrees with Trump that there's a difference between absentee voting, in which voters request a ballot, and vote-by-mail programs, where jurisdictions automatically send ballots to registered voters.

• McCarthy sees vote by mail as particularly problematic in states that don't have the infrastructure to handle such ballots on a massive scale.
• But he said most Americans don't get the distinction.

Reality check: There's no evidence that voting by mail is plagued by fraud. Trump himself voted by mail in Florida last month.