Of the donors who gave at least $200 to Jeb Bush, Gov. John Kasich, Gov. Chris Christie or Senator Lindsey Graham in the Republican primaries, more of them have also contributed to Mrs. Clinton than to Mr. Trump, according to Federal Election Commission filings through June.

People who give to multiple candidates are a small percentage of Republican donors. Of the donors to Mr. Bush who also gave to one of the current nominees, 303 — more than 2 percent of the total — gave to Mrs. Clinton. Less than 1 percent of them gave money to Mr. Trump, the filings showed.

Those crossover donations are adding up. Mrs. Clinton has received $2.2 million from donors to candidates who dropped out of the Republican presidential primary, about $600,000 more than Mr. Trump has received from such donors, the filings showed.