photo by: AP File Photos

Kansas Republican Senate candidate Roger Marshall, left, and Democratic Senate candidate Barbara Bollier, right.

TOPEKA (AP) — Democrat Barbara Bollier has raised $4.3 million this month for her campaign for Kansas’ open U.S. Senate seat, extending her fundraising advantage over Republican Roger Marshall and boosting her state record for fundraising to nearly $25 million.

Bollier, a Kansas City-area state senator, has raised more than five times as much money so far in October as Marshall, a two-term congressman for central and western Kansas, according to reports filed by their campaigns. Marshall’s total for October so far was about $791,000, to bring his fundraising to about $6.3 million, including contributions to his GOP primary race.

Democratic candidates across the U.S. have seen a flood of contributions as their party seeks to overturn the GOP’s 53-47 Senate majority.

The Marshall-Bollier race has become Kansas’ most expensive political contest. The campaigns and outside groups are expected to spend more than $55 million on advertising by the Nov. 3 election, according to the media tracking firm Kantar/CMAG.

Bollier’s campaign is far outspending Marshall’s campaign on advertising, but Marshall is getting a far bigger boost from outside groups. Republican groups are set to spend more than $30 million, while the figure for Democratic groups is just short of $10 million.