Sharp differences over spending and strategy are cleaving House Republicans as the two main groups charged with saving the party’s embattled majority in the midterm elections go separate ways in key suburban battlegrounds.

Congressional Leadership Fund, the super PAC aligned with senior GOP leaders, canceled advertising in the expensive Denver media market, and never invested in costly D.C., concluding vulnerable Reps. Mike Coffman, R-Colo., and Barbara Comstock, R-Va., couldn’t hold their suburban districts and that the money would be better spent elsewhere.

But the National Republican Congressional Committee, the party’s official House campaign arm, continues to invest millions in Colorado’s 6th Congressional District and Virginia’s 10th, despite being outgunned and outmanned by Democrats there and in several other seats across the country poised to fall to the Democrats.

“There are just some fundamental disagreements over how and where [CLF and NRCC] should be spending,” a Republican operative involved in House races said, requesting anonymity in order to speak candidly about the groups' competing game plans.

Democratic candidates and allied organizations have more resources to invest in House races than their Republican counterparts. Among candidates, the Democrats’ financial advantage was approximately $50 million, while just among the parties’ two campaign arms, the Democratic Congressional Campaign Committee had around $20 million more to spend than the NRCC.

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With the 2018 battlefield expanding since Labor Day, CLF decided at the end of September that the millions earmarked for Coffman, and any cash it might spend on Comstock, could be allocated more efficiently, giving the GOP a chance to preserve more seats. The super PAC made its decision after reviewing the data and watching bullish Democrats bullish reduce their planned investments in each seat over time.

CLF has its critics, however. Of the whopping $150 million-plus the group projects it will raise this election cycle, a considerable sum has been sunk into an extensive voter turnout program, complete with data analytics, field offices, and paid staff. Some Republican operatives say the pricey task should have been left to the Republican National Committee. The super PAC has made more than 25 million voter contacts since early last year, including in competitive districts where it was the only GOP group knocking on doors.

CLF spokeswoman Courtney Alexander defended the group's strategy. “We’re proud that CLF’s record-breaking fundraising has allowed us to do things differently in a tough environment, including launching our unprecedented field program while tripling our advertising budget over last cycle,” she said.

Meanwhile, Republicans who agree with the CLF approach are insinuating, quietly, that the NRCC’s dogged support for Coffman and Comstock could cost the GOP the majority by leaving too many vulnerable incumbents insufficiently protected — especially those who are better positioned to withstand the blue tide if they receive enough help. Through Nov. 6, the NRCC has more than $6 million combined in television airtime reserved in Denver and D.C., in addition to what the committee has spent to date.

Of the 31 seats rated a “tossup” by the nonpartisan Cook Report, the NRCC is only playing in 14 of them. That means teetering Republicans like Reps. Mimi Walters, in Orange County, Calif.; Peter Roskam, in Illinois’ Chicago suburbs; and Dave Brat, in Virginia’s Richmond suburbs, aren’t receiving air cover from the NRCC's independent expenditure unit; neither are Reps. Andy Barr, R-Ky., Bruce Poliquin, R-Maine, or Rep. David Young, R-Iowa.

But the NRCC believes its strategy, while counterintuitive, is paying dividends. By forcing Democrats to spend in Colorado 6 and Virginia 10, there is less money to throw against other endangered Republicans who aren’t as well known or battle tested as Coffman and Comstock. Essentially, the two are being used as cover to distract Democrats from easier targets. Additionally, some incumbents, like Roskam, are to begin benefiting from NRCC advertising in the form of "hybrid" ads that are coordinated with the candidate.

“Our strategies compliment each other very well,” NRCC spokesman Matt Gorman said, referring to CLF. “What we’ve seen with Colorado and [Comstock’s] race is that it’s essentially tied.” Gorman was referring in part to a fresh internal poll from Comstock’s campaign that put her in front by 1 point.

House Republicans are defending a 23-seat majority amid severe political headwinds fanned by dissatisfaction with President Trump. The NRCC and CLF are both claiming internal polling shows their candidates benefited from the contentious battle to install newly minted associate Justice Brett Kavanaugh on the Supreme Court.

The generic ballot, gauging which party voters would prefer be in charge of Congress, suggests otherwise. In polls from CNN and Morning Consult taken at the apex of the Kavanaugh clash and in the immediate aftermath, Democrats led by 13 percentage points, and 10 points, respectively.

Either way, Republicans are struggling less than four weeks before Election Day to hold the line on hostile terrain against a Democratic surge fueled by more cash, more soldiers, and more voter enthusiasm. That has ratcheted up the pressure on CLF and the NRCC, and sparked sort of internal, Monday-morning quarterbacking in GOP circles that typically roils the party under fire.

“There are a lot of people who second guess you, but they don’t have the information you have. You’re weighing each district against the full country and need to prioritize races you think you can have the most impact,” said Carl Forti, the Republican strategist who ran the NRCC’s independent expenditure advertising campaign in 2006, when Democrats rode a massive blue wave to control of the House and Senate.

“Cost of market alone is not a deciding factor,” Forti continued. “If I can have the most impact in an expensive market then that’s where you spend. Yes, that money may help you in three other districts, but those three others might not be as winnable, or there are other factors at play that the person criticizing isn’t considering.”

Correction: CLF never reserved any television advertising time in the Washington, D.C., media market. This story has been updated to reflect that.