The Republican machine is spending money in Montana to ensure the party holds an open House seat in an upcoming special election.

Congressional Leadership Fund, the super PAC affiliated with House Speaker Paul Ryan, R-Wis., is investing seven figures on advertising and field operations. The National Republican Congressional Committee is set to spend nearly $300,000 on television and digital advertising.

The Wall Street Journal's Reid Epstein first reported the news.

The Montana at-large seat opened up this year when Ryan Zinke resigned to become Interior secretary. Montana leans Republican, and the statewide at-large seat has been held by a Republican for the past 20 years. But Montana's Democratic Party is in good shape, holding power in state government and controlling one U.S. Senate seat.

Given that, Republican insiders say the party doesn't want to take any chances. That's especially the case after a Tuesday special election in Kansas to fill a vacant House seat there.

Republicans won, but the margin was closer than expected, and the GOP doesn't want to get caught flat-footed in Montana. In that May 25 contest, Greg Gianforte, the Republican nominee for governor last year, is facing Democratic activist Rob Quist.

President Trump's son, Donald Trump, Jr., is scheduled to travel to Montana to stump for Gianforte.