U.S. Sen. Elizabeth Warren, D-Massachusetts, continued her high-power fundraising this summer, raking in another $3 million for her 2018 re-election bid between July and September, campaign officials reported Friday.

The high-profile Massachusetts Democrat, who faces a series of Republican challengers in 2018, reportedly collected a total of $2.98 million in the third fundraising quarter of 2017 -- about $1 million per month, according to her campaign.

Although the amount collected over the three-month period is a slight drop from the $3.45 million and $5.2 million she reportedly raked in during the respective second and first quarters of 2017, it brings Warren's campaign war chest to nearly $13 million with just over a year left before the 2018 contest -- up from $11 million in June and $9.2 million in March.

Similar to previous fundraising periods, Warren's campaign contended, most of the donations made to the senator's re-election bid were small dollar amounts.

Nearly all, or 99 percent, of funds given were $100 or less; 94 percent were $50 or less; and 78 percent were $25 or less, according to data Warren's campaign released ahead of the Federal Election Commission's October reporting deadline.

Officials with the Democrat's campaign did not release the total number of donors to Warren's re-election bid or how much it spent between July and the end of September.

They, however, noted that Warren's third quarter fundraising total included contributions from 7,586 Massachusetts residents -- down from the nearly 9,400 who donated to her re-election last quarter.

In total, nearly 38,500 Massachusetts residents had contributed to Warren's 2018 campaign this cycle as of the end of September, according to the Democrat's campaign.

Warren's fundraising came despite a Republican National Committee-backed campaign aimed at unseating the Democrat, as well as challenges from a series of GOP candidates.

Among those aspiring to unseat Warren is Republican businessman John Kingston, who recently announced that although his campaign was still formally in the exploratory phase, he had loaned $3 million of his own money and raised $256,000 for his bid.

Republican Senate hopeful Beth Lindstrom, a former aide to Mitt Romney and manager of Scott Brown's 2010 Senate campaign, meanwhile, is expected to raise money at the National Republican Senatorial Committee headquarters in Washington later this month, the Boston Globe reported.

State Rep. Geoff Diehl, R-Whitman; entrepreneur Shiva Ayyadurai, of Cambridge; Allen Rodney Waters, of Mashpee; Darius Mitchell, of Lowell; Heidi Wellman, of Braintree; have also filed to run as Republicans for the Massachusetts Senate seat in 2018.