House Speaker Paul Ryan tells lawmakers he won't 'defend' Trump

US House Speaker Paul Ryan, the nation's top elected Republican, told lawmakers today he will no longer "defend" or campaign with presidential nominee Donald Trump, focusing instead on maintaining his party's majority in Congress.

But Ryan, who has had a testy relationship with the provocative billionaire from the start and has criticised him on numerous occasions, stopped short of rescinding his endorsement, according to a person who listened to the conference call.

Ryan "said he will not defend Trump or campaign with him for the next 30 days," the source on the call said.

But a spokeswoman for Ryan, AshLee Strong, told reporters after the call that there was "no update in his position at this time" in terms of endorsing Trump.

The speaker will "spend the next month focused entirely on protecting our congressional majorities," Strong said in an email.

But the source on the call appeared to suggest Ryan had effectively conceded the election to Trump's Democratic rival Hillary Clinton, who is leading in national polls and in several key battleground states.

"He will spend his entire energy making sure that Hillary Clinton does not get a blank check with a Democrat-controlled Congress," the source said.

The speaker, addressing House Republicans in a call to members of his conference, appeared to give lawmakers the green light to cut ties with the controversial GOP nominee.

"You all need to do what's best for you in your district," Ryan said, according to the person on the call.

Trump's candidacy suffered a crippling blow after a 2005 tape was released Friday in which he made lewd and derogatory comments about women, including his ability to grab them by the crotch with impunity because, as a celebrity, "you can do anything.