Republican groups have begun shifting the party's television spending with about five weeks to go until Election Day, cutting loose some vulnerable Republicans to shore up its push to protect the House majority. 

In recent days, GOP groups have pulled significant ad dollars from four incumbent House members—Colorado Rep. Mike Coffman, Michigan Rep. Mike Bishop, Kansas Rep. Kevin Yoder and Pennsylvania Rep. Keith Rothfus—according to reporting by NBC and other outlets, as well as television-spending data. 

Late last month, the National Republican Congressional Committee cancelled its ad buys in Rothfus's district as the incumbent continues to poll poorly against Democratic Rep. Conor Lamb. That move is leaving Rothfus to fend for himself—his campaign is the only Republican group with ads on the air in the district through Election Day, according to Advertising Analytics. 

And now the GOP is pulling television dollars from three more congressmen. 

On Friday, Congressional Leadership Fund cancelled its future buys in both Coffman and Bishop's districts. While Coffman has repeatedly bested Democrats in tough races in past elections, recent polling shows Democrat Jason Crow leading. 

The Bishop move raised some eyebrows among Republicans since that race is seen as more competitive—Cook Political Report rates the race a toss-up. But even without CLF, Bishop is far from on his own, as Republicans are still outspending Democrats there. Politico first reported those decisions.

Courtney Alexander, CLF's communications director, said in a statement that the group will "continue to run strong field operations in these districts and will continue to conduct polling and evaluate races across the country as we do everything we can to protect the Republican Majority."

And over the weekend, the National Republican Congressional Committee axed $1 million in television buys that would have boosted Yoder, who finds himself in a difficult climb against Democrat Sharice Davids. The Hill first reported that NRCC decision.

Tough choices like these are a hallmark of the final stretch before every election, but they are especially notable this cycle as Republicans stare down a daunting and expanded battleground that puts dozens of incumbents at serious risk of defeat. 

But as CLF pulls out of those two districts, a source familiar with the group's spending told NBC News that it's adding $5 million in television advertising in the Los Angeles market, which touches a half-dozen of the most competitive districts of the cycle.

It's also putting $200,000 into Iowa's 3rd Congressional District, where GOP Rep. David Young faces Democrat Cindy Axne; $1 million into Wisconsin's 1st Congressional District, where Republican Bryan Steil is running against Democrat Randy Bryce; and $225,000 into New Mexico's 2nd Congressional District, where Republican Yvette Herrell and Democrat Xochitl Torres Small face off.