The prospect of a Donald Trump nomination is accomplishing what a diverse and talented field of Republican presidential contenders could not: uniting the party’s big-money donor establishment.

Some of the wealthiest conservative givers in the country are helping pay for a series of last-ditch attacks to wound 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 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.