Speaker Paul Ryan told donors at a private meeting in Colorado last week that they shouldn't concentrate so much on the GOP keeping control of the Senate because the Republican majority in the House was in jeapordy. 

The Hill:

During the conference, the speaker said donors shouldn't put their focus completely on retaining the Senate, and noted that Republican control of the House may also be at risk, the Times reported, citing a Republican who heard the talk.

There is reportedly growing concern among the party's biggest contributors over retaining control of Congress with Donald Trump as the party's nominee.

Democrats would need to pick up more than 30 House seats to take control. But according to the Times, Republicans are worried about a scenario in which they lose enough seats that Ryan is weakened and the party is on the defensive.

The Times report on Saturday painted a broad picture of Republicans worried about the impact of Trump on down-ballot races.

The party's nominee has had a difficult two weeks, capped off by the overwhelming criticism over his fight with the family of Capt. Humayun Khan, a Muslim-American soldier killed in 2004 in Iraq.

Trump also last week declined to endorse Speaker Ryan and Sen. John McCain (R-Ariz.). But the GOP nominee announced Friday he had decided to support the candidates. 

Ryan said last week his endorsement of Trump shouldn't be seen as a blank check, noting the candidate's campaign has had a "pretty strange run since the convention."

Polls have also shown Hillary Clinton with a strong bounce after last week's Democratic convention. Clinton is leading in a number of polls nationally and in key battleground states, adding to Republicans worries.

Donors had hoped Trump would begin to shift his focus ahead of the general election.

Current projections show the Democrats picking up a possible 18-24 seats - short of a majority. But with Trump's polls bouncing up and down, an element of nervous uncertainty has crept into the deliberations of donors. If Trump can stay within 5 or 6 points of Clinton, the likelihood of a Democratic wave election recedes. 

But if a Clinton landslide of 10 or more points happens, up to a dozen more GOP seats would be vulnerable. 

Trump can't afford to fundraise for individual House and Senate members, given his own dire financial straits, so the donors become even more important to the GOP maintaining its majority. Ryan may have overstated the worst case scenario, but given what's happened so far in the campaign, he was not out of bounds mentioning it.