Trump fires back at Ryan as Republicans go to war

Donald Trump has gone on the offensive against the highest profile Republican to stop defending him, House Speaker Paul Ryan, who he described as a "weak and ineffective leader".

The highest elected GOP member in the US said he could no longer defend the actions of the presidential nominee as dozens of others withdrew their support for the New York businessman following his controversial comments regarding sexual assault last weekend.

"Our very weak and ineffective leader, Paul Ryan, had a bad conference call where his members went wild at his disloyalty," Trump tweeted on Tuesday.

The split within Republican ranks is growing more and more chasmic by the day as Trump trails Democrat Hillary Clinton in the majority of polls, some by double digits.

Trump also claimed victory in Sunday night's televised debate between himself and Clinton, as well as aiming another swing in Ryan's direction.

"Despite winning the second debate in a landslide (every poll), it is hard to do well when Paul Ryan and others give zero support!," he added.

A recording was released by the Washington Post last Friday which appeared to show the tycoon bragging about committing sexual assault on several women.

The Republican nominee has a significant deficit to overcome ahead of the election on November 8, and believes that he can do it without the support of a large portion of his party's lawmakers.