NYT:

Some of the wealthiest conservative givers in the country are helping pay for a series of last-ditch attacks to wound Mr. Trump, disclosures filed on Sunday night revealed, even after previously backing rival Republican candidates. And officials involved with the political groups have made clear that they are aggressively raising more money to fight Mr. Trump, hoping to deprive him of enough delegates to win the Republican nomination outright. That would set the stage for a contested convention in July.

Our Principles PAC, a group set up to highlight Mr. Trump’s past liberal positions, took in $4.8 million last month, with a roster of donors that shows it has significantly expanded beyond the Ricketts family, which provided the group’s early funding.