U.S. Sen. Elizabeth Warren, D-Massachusetts, continued her high dollar fundraising this Spring, bringing in another $3 million for her re-election campaign in the quarter that ended in June, officials announced Tuesday.

Warren, who had been on pace to raise $1 million per month for her re-election, maintained that trend with $2.93 million raised between April and June 30 -- bringing her war chest to a total of $15.6 million, according to her campaign

That amount, which Warren's campaign said primarily consisted of donations of $100 or less, represented a slight increase from the $15 million cash balance the incumbent senator reported at the end of March.

Warren's campaign did not provide details on the campaign's spending during the three-month period or other information on donors outside of the state -- data that must be reported to the Federal Election Commission by July 15.

Officials, however, offered that more than 8,500 Massachusetts residents donated to the Democrat's re-election bid during the second quarter of 2018 and that the campaign is just shy of hitting one million total contributions.

Warren touted the milestone in a Monday fundraising email to supporters.

"Some politicians might say: Big deal! I can just get a big corporation to write a check for any amount I want - I don't need a million donations. But I would rather take a million small donations from people who believe in this fight than be bought by a Wall Street billionaire or powerful interest group," she said.

The senator began 2018 with $14.1 million in campaign cash. She raised $3.1 million and reported spending $2.2 million for her re-election bid between January and March, according to FEC data.

Warren, an oft-rumored 2020 presidential contender, faces a Republican National Committee-backed campaign aimed at unseating her and challenges from three GOP candidates: Beth Lindstrom, a former aide to Mitt Romney and manager of Scott Brown's 2010 Senate bid; John Kingston, a Winchester businessman; and state Rep. Geoff Diehl, R-Whitman -- the Massachusetts Republican Party's endorsed candidate.

As of the end of March all three candidates lagged far behind Warren in terms of fundraising.

Diehl reported a cash balance of $226,195, while Lindstrom's campaign had $99,277 cash-on-hand. Kingston, meanwhile, reported a cash balance of nearly $3.1 million.

Kingston's campaign announced late Monday that the Republican "will report a commanding campaign war chest of over $2.65 million cash-on-hand and approximately $316,000 raised for the second quarter of 2018."

Officials added that, like Warren, most of Kingston's campaign contributions came from small donors.

"I am incredibly excited with the support our campaign is earning from hardworking voters who are eager to retire Sen. Elizabeth Warren and her toxic brand of Washington politics," he said in a statement. "Our campaign's building momentum is a sign Massachusetts voters are eager to elect a senator who will put their interests over personal ambition and a partisan agenda."