PAUL RYAN: I will no longer defend Donald Trump or campaign for him
"The speaker is going to spend the next month focused entirely on protecting our congressional majorities," Zach Roday, press secretary for the speaker's political office, later said in a statement.
According to the source on the call, Ryan told members to "do what's best for you in your district."
Ryan, however, maintained his endorsement of the brash billionaire.
"There is no update in his position at this time," Roday said.
Ryan also told Republicans that he was willing to endure political pressure and do what was necessary to protect the GOP majority, the source on the call said. The source said Ryan would spend his "entire energy" making sure Democratic nominee Hillary Clinton does not get a "blank check" with congressional majorities.
The House speaker has campaign events for members of Congress scheduled in 17 states and 42 cities in October.
A firestorm of controversy was ignited on Friday when a 2005 audio tape leaked in which Trump boasted about kissing and groping women.
Trump apologized for the remarks in a video published just after midnight on Saturday, but many congressional Republicans are worried the comments and Trump's high negatives could put their own races in jeopardy.
An avalanche of prominent Republicans condemned Trump's comments and some, including No. 3 Senate Republican John Thune of South Dakota, have gone as far as to call on the billionaire to step down as the nominee and hand the ticket over to vice presidential nominee Mike Pence.
Trump has refused to obey such calls. Instead, he doubled down during Sunday's debate, going on the offensive by pointing to former President Bill Clinton's history with women.
The relationship between Trump and Ryan has been lukewarm throughout the election. Ryan shocked the political world when he initially refused to offer the real-estate tycoon his endorsement after he had secured the GOP nomination. The House speaker later endorsed Trump, explaining that he thought the billionaire would be a better partner to work with to push through a conservative policy agenda.