By BOBBY CAINA CALVAN, Associated Press

HELENA, Mont. (AP) — National Democrats have increased their investment in this month's Montana special congressional election, but whether it will make a difference remains to be seen as Republicans have poured in surprisingly large amounts of money to protect a seat their party has held for two decades.

Earlier this week, the Democratic Congressional Campaign Committee announced that it would spend another $400,000 to help candidate Rob Quist, a musician and first-time office seeker. The money will be used to pay for television ads and field workers to push Democrats to vote in the May 25 special election to fill Montana's only seat in the U.S. House.

The latest spending is on top of the $200,000 the committee pledged last month amid frustration by some national and Montana Democrats who scolded their party for not doing more to support candidates running in special elections across the country.

But as progressives push back against advances from conservatives, Republican groups are taking no chances and are pouring large amounts of money into campaigns, even in relatively safe districts like the one in Montana.

Vice President Mike Pence plans to travel to Montana next week, as does the president's son Donald Trump Jr., to campaign for their fellow Republican. The vice president's office said Friday that Pence is expected to campaign for Gianforte during the weekend of May 13, although details were still being finalized.

"They don't want the race to be too close because that would make congressional Republicans reluctant to cast tough votes for the Trump administration," said Jeremy Johnson, a professor of political science at the Carroll College in Helena. "The skittish members will be nervous that they could lose their seats especially in swing districts across the country."

The Congressional Leadership Fund recently poured in another $500,000 to support Republican Greg Gianforte's ground game — on top of the $1.5 million already invested on television spots that attack Quist for unpaid bills and paying his taxes late.

"It would be political malpractice to not define Rob Quist for the flawed candidate he is," said Courtney Alexander, a spokeswoman for the Republican group.

The National Rifle Association has spent and the National Republican Congressional Committee have also bought air time this month for their own anti-Quist ads.

Quist has gotten outside help from the Planned Parenthood Action Fund and the Progressive Turnout Project.

In the final weeks of the campaign, Gianforte forces are spending $2.6 million to bombard the state with television ads, while Quist has thus far secured less than a fifth of that amount for his own TV spots.

Over the years, the DCCC has usually not been a big spender on congressional races in Montana, even though national Democratic groups have spent heavily to support candidates for governor and expect to do so to re-elect Sen. Jon Tester in 2018.

Last month, Vermont Sen. Bernie Sanders pointedly criticized national Democrats for not quickly coming to the aid of a Kansas Democrat who came within 6.8 percentage points of beating a Republican in a district Trump won by 27 points in November.

Democrats may be spending in the Montana race because they don't want to again be accused of abandoning one of their candidates, said David Wasserman, who handicaps House races for the Cook Political Report.

"It's to take a shot but also to appease Democrats who want to compete in every single race," Wasserman said. "If Quist comes within single digits of Gianforte, it would be a good sign for Democrats nationally."

Montana Democrats like Jessica Karjala, who serves in the state House and will be campaigning across her Billings district for Quist, say the money from the party may not match Republican spending, but it's well-timed as the election draws near.

"The $400,000 might be peanuts by comparison, but it's better than a sharp stick in the eye," Karjala said.