WASHINGTON - With less than eight weeks to go before voting begins in Texas, a crowded field of Democrats has raised more than $2.8 million in a primary battle to take on Rep. John Culberson, R-Houston, who has struggled to keep up with the Democrats' top fundraiser.

Democrats hoping to strip President Donald Trump of his majorities in the House and Senate in 2018 have set their sights on three Republican-held congressional districts in Texas that Hillary Clinton won in 2016. One of them is the 7th Congressional District in Houston and western Harris County represented by Culberson.

But flipping a congressional seat takes money, and all but one of the seven Democratic hopefuls - assistant city attorney James Cargas - are largely unknown first-time candidates for federal office.

The winner in the money chase so far is nonprofit executive Alex Triantaphyllis, who raised over $255,000 in the fourth quarter of 2017, bringing his total raised for the election to over $925,000. After expenses, that leaves him over $630,000 cash on hand heading into the final stretch of the March 6 primary.

Culberson, a 17-year incumbent who trailed Triantaphyllis in fundraising at the end of September, responded in the last three months by raising more than $345,000, bringing his year-end total to over $949,000.

But Culberson's campaign also has been burning through money more quickly than Triantaphyllis, leaving him with about $595,000 in the bank - a slightly smaller war chest than the Democrat's.

Culberson ended the third quarter of 2017 - the end of September - with more than $645,000 in receipts, trailing Triantaphyllis' $668,000. Culberson's war chest of nearly $390,000 at the time also was dwarfed by the $535,000 Triantaphyllis had at his disposal, raising alarms in GOP circles.

While Culberson, a top Republican on the House Appropriations Committee, had narrowed the gap, he has not shown the usual outsized incumbent advantage in campaign fundraising. Unlike all the Democrats in the race, however, he does not face a well-funded primary opponent.

Three other Democrats have shown their fundraising chops ahead of the Jan. 31 Federal Election Commission deadline.

Laura Moser, a writer and national anti-Trump activist, said she raised about $215,000 in the fourth quarter of 2017, bringing her total to about $616,340.

Another top fundraiser in the Democratic primary is Houston attorney Lizzie Pannill Fletcher, who had raised more than $550,000 by the end of September, trailing only Triantaphyllis and Culberson. She has since raised some $200,000 more, bringing her total to more than $750,000, leaving about $400,000 in cash on hand.

Houston physician Dr. Jason Westin, a researcher at MD Anderson Cancer Center, reported $123,369 in fourth-quarter fundraising, bringing him up to a total of $421,303 for the election so far. He goes into the final primary stretch with $218,773.

All the Democrats have emphasized their success with small-dollar donors, reflecting Democratic energy in the first year of the Trump presidency. Triantaphyllis said over two-thirds of his contributions in the fourth quarter were $100 or less. Moser boasted of more than 5,700 individual contributions in 2017 from donors in all 50 states and the U.S. territory Guam.

Much of the Democratic messaging so far has focused on Trump, whose faltering poll numbers could damage the Republican brand in largely affluent, educated, urban districts like Culberson's.

Westin recently released a video attacking what he calls "the anti-science and anti-fact disease infecting our politics."

Three other Democrats have yet to provide 2017 totals: Cargas, making his fourth bid for the seat, reported some $46,000 in receipts at the end of September. Two other Democrats pulled in lesser amounts: Joshua Butler, an administrator at the University of Texas' Health Science Center, reported more than $28,000 in fundraising; Debra Kerner, an educator who served on the board of the Harris County Department of Education, had raised more than $18,000.

The Jan. 31 deadline marks the last major federal filing deadline before the March 6 primary. For Democrats trying to turn Texas blue, the district represents an important benchmark, as well as a top pickup opportunity nationally. Clinton won District 7 by 1.4 points in November 2016, along with Republican-held districts outside San Antonio and Dallas.