A wealthy Massachusetts businessman and outspoken opponent of President Trump has launched a Republican bid for U.S. Senate, setting up a potentially divisive primary fight against a Trump loyalist.

John Kingston, a GOP activist and fundraiser who backed an anti-Trump group in 2016, opened up an exploratory campaign account this week and is “strongly considering” jumping in the GOP race to run against incumbent Democrat Elizabeth Warren.

Kingston has already pumped $2 million of his own money into his likely candidacy, an adviser told the Herald.

The Winchester businessman and philanthropist only recently switched from independent to Republican. His newly launched website, johnkingston.com, promotes him as an “independent” voice.

“Elizabeth Warren represents more of the same divisive politics that has failed our country,” Kingston said in a statement. “We need independent leadership that will focus on making our Commonwealth stronger and more just.”

Kingston’s candidacy is likely to trigger a bruising primary battle on the GOP side. He would be the second Republican to file an exploratory campaign bid for Warren’s U.S. Senate seat, behind state Rep. Geoff Diehl, who co-chaired Trump’s campaign in Massachusetts.

Diehl has already launched his campaign and likely will get the backing of Trump supporters in Massachusetts. Republican Shiva Ayyadurai is also considering a U.S. Senate run.

Kingston switched from Republican to unenrolled in 2016 in protest against Trump but has since switched back to a registered Republican voter, according to an aide. Kingston opened a federal campaign account on Thursday, according to the aide.

Kingston, who was a major donor to former Gov. Mitt Romney, is believed to have the unofficial backing of Gov. Charlie Baker and the state Republican establishment in Massachusetts.

Kingston has already hired a GOP consultant from Pennsylvania, Mark Harris, to be his chief strategist.

Harris said Kingston is hiring other staffers and raising money but also plans to use his personal wealth to finance the race.

Kingston last year founded Better for America, a group that at one time was trying to get ballot access for an independent presidential candidate, Evan McMullin. The effort, which folded, was viewed by many Republicans as an attempt to thwart Trump’s candidacy.

Kingston is a retired investor and currently runs a nonprofit called Sword and Spoon Group, a faith-based organization that runs a Christian retreat in Vermont and a filmmaking group, Kingston Road Pictures.