When President Donald Trump connected by phone last week with Republican megadonor Sheldon Adelson — perhaps the only person in the party who can cut a nine-figure check to aid his reelection — the phone call unexpectedly turned contentious.

The 87-year-old casino mogul had reached out to Trump to talk about the coronavirus relief bill and the economy. But then Trump brought the conversation around to the campaign and confronted Adelson about why he wasn't doing more to bolster his reelection, according to three people with direct knowledge of the call. One of the people said it was apparent the president had no idea how much Adelson, who's donated tens of millions of dollars to pro-Trump efforts over the years, had helped him. Adelson chose not to come back at Trump.

When word of the call circulated afterward, Republican Party officials grew alarmed the president had antagonized one of his biggest benefactors at a precarious moment in his campaign. They rushed to smooth things over with him, but the damage may have been done.

Adelson's allies say it's unclear whether the episode will dissuade the Las Vegas mogul — long regarded as a financial linchpin for Trump's reelection — from helping the president down the home stretch.