With just three weeks until the midterm elections and control of Congress on the line, a major Republican money group is telling voters their choice this fall comes down to deciding between President Donald Trump and House Minority Leader Nancy Pelosi.

The Congressional Leadership Fund super PAC, which is aligned with retiring House Speaker Paul Ryan, is starting its new messaging campaign in areas including upstate New York's 22nd District, where incumbent GOP Rep. Claudia Tenney faces a challenge from Democrat Anthony Brindisi.

In a new ad first provided to CNBC, the PAC links Tenney to Trump while arguing that Brindisi, a state assemblyman, will be an ally of Pelosi. The ad will start airing in Binghamton and Utica markets, as well as on digital platforms throughout the district.

The group will soon hammer the Trump vs. Pelosi theme across the country. According to a source close to the committee, the PAC will unleash similar attack ads in key battleground districts as November approaches.

"President Trump is a powerful motivator for Republican voters and his presence on the campaign trail this fall will help win several key races across the country," Corry Bliss, CLF's executive director, said in a statement.

Pelosi is a favorite target of Republicans, but her spokesman says the tactic isn't resonating with the electorate.

"Republicans are on the brink of losing their House Majority and they are flailing. Poll after poll shows that attacking Nancy Pelosi just isn't the Hail Mary they hoped it would be," said Drew Hammill, Pelosi's deputy chief of staff. "Their strategy to hold the majority is crumbling before their eyes."

Later, the Brindisi campaign responded to the ad and pushed back on the idea that he would support Pelosi's agenda if he were to be elected.

"He's been clear that in Congress he won't support Nancy Pelosi for speaker," Brindisi campaign manager Ellen Foster said. "Instead of working to fix our broken immigration system with bipartisan comprehensive immigration reform, Claudia Tenney and her allies are distorting Anthony's record to divide Upstate New Yorkers."

Representatives for Tenney and Trump did not return requests for comment.