Later this month, Romney will take his most aggressive step yet to insert himself into the 2020 campaign when he hosts a New York City fundraiser for Maine Sen. Susan Collins, Colorado Sen. Cory Gardner and Michigan Senate hopeful John James. All are establishment-aligned figures confronting tough races in swing states. Behind the scenes, Romney’s team has also begun directing his donors to help GOP candidates in Senate battlegrounds.

Romney aides say he’s always intended to help in competitive Senate races and that his desire to do so has never been influenced by Trump’s efforts to ostracize him. Yet the senator’s recent efforts underscore his insistence on not receding from a Republican Party now dominated by Trump. At 72 and in the twilight of his political career, Romney cares little about what the president has to say about him, his friends say, and is determined to take a stand for mainstream Republicans who’ve been increasingly marginalized since Trump took office.

“I know plenty of my candidates would love Romney’s fundraising help — he’s got a huge donor network, regardless of the Twitter sentiment of the day,” said Will Ritter, a top aide on Romney’s 2018 Senate campaign, referring to Trump’s attacks.