BOSTON — The Republican campaign to oust Democratic U.S. Sen. Elizabeth Warren in next year’s election is starting to shape up and it’s pitting the conservative wing of the GOP against its more moderate middle.

The latest candidate to jump into the running is Winchester business executive John Kingston.

Although Kingston has yet to make a formal announcement, he’s set up a campaign account and issued a statement urging the Massachusetts Republican State Committee to adopt a resolution “condemning bigotry and hate speech.”

“It is impossible to achieve what we need to in this country if we are divided by bigotry, discord and hate-fueled violence,” he wrote, following an Aug. 12 white supremacist rally in Charlottesville, Virginia.

Another more moderate GOP candidate is Beth Lindstrom.

The aide to former Massachusetts governor and GOP presidential nominee Mitt Romney announced her candidacy in a recent video message. In it, the Groton resident described herself as a “mom” and an “independent-minded Republican.”

“Some days I look at what’s happening in Washington and I just shake my head,” Lindstrom said. “The politicians like to think the problem is all on the other side but the truth is there’s plenty of blame to go around.”

On the more conservative and libertarian side is state Rep. Geoff Diehl, of Whitman, and Cambridge technology entrepreneur Shiva Ayyadurai.

Diehl served as co-chairman of Trump’s campaign in Massachusetts. He supports efforts to repeal and replace former President Barack Obama’s health care law and has defended Trump’s call for a ban on transgender troops serving in the U.S. military.

He’s also criticized Warren, saying she’s neglected Massachusetts for four years and is now “trying to fool voters into believing she cares.”

Ayyadurai participated in a rally led by conservative activists on Boston Common that drew thousands of counterprotesters.

Ayyadurai, flanked by supporters holding “Black Lives Do Matter” signs, blasted the media, “fake news,” academia, GMOs, and Democrats, and said “Elizabeth Warren supported superpredator Hillary Clinton.” He’s also adopted the campaign slogan: “Only a real Indian can defeat the fake Indian,” a reference to Warren’s claim of Native American heritage.

A fifth candidate, Allen Waters, of Mashpee, describes himself on his website as a middle-class family man with blue-collar roots who is “fiscally responsible, socially conscious, believes in traditional American Values, follows the Constitution, and is a strong advocate for ordinary Americans.”

Warren has responded by ramping up her campaign activity, attending 13 town hall meetings across the state this year, most recently in Dartmouth, Marshfield and Concord.

Warren, who is frequently mentioned as a potential White House contender in 2020, also holds a daunting fundraising advantage. As of the end of June, she reported a hefty $11 million in cash in her campaign account.

By contrast, Diehl had $260,000 in cash, Ayyadurai had $28,000 and Waters had just $741. Kingston and Lindstrom announced their candidacies after the most recent campaign filing deadline, although a Kingston spokeswoman said he’s already poured $2 million of his own money into his campaign.

Gov. Charlie Baker, the state’s top Republican, hasn’t backed any of the candidates yet. Baker is considered a moderate Republican, having opted not to vote for Trump during last year’s election.

Although he remains popular among voters, the Senate race could play into his political fortunes. Baker faces re-election next year and Democrats will try to tie him to whichever candidate wins the GOP Senate primary, forcing him to support or disavow the candidate much the way he was ultimately pressured to disavow Trump.

Other higher-profile Republicans opted out of the Senate race, including former Boston Red Sox pitching great Curt Schilling, who briefly flirted with the idea of challenging Warren.

Diehl said he’s received Schilling’s backing.