Donald Trump
Trump's attack on Ryan comes a day after the House Speaker said that he would not defend or campaign for the Republican presidential nominee anymore.Reuters

United States Republican presidential candidate Donald Trump on Tuesday lashed out at Speaker Paul Ryan and other Republicans for withdrawing their support four weeks into the elections. He described Ryan as a "weak and ineffective leader" in a series of posts on Twitter:

"Despite winning the second debate in a landslide (every poll), it is hard to do well when Paul Ryan and others give zero support! Our very weak and ineffective leader, Paul Ryan, had a bad conference call where his members went wild at his disloyalty," Trump wrote adding that it was "nice that the shackles have been taken off me and I can now fight for America the way I want to."

He further added: "With the exception of cheating Bernie out of the nom the Dems have always proven to be far more loyal to each other than the Republicans! Disloyal R's (Republicans) are far more difficult than Crooked Hillary. They come at you from all sides. They don't know how to win - I will teach them!" 

Trump also accused "foul-mouthed" Senator John McCain of dropping him over "locker room remarks" after having begged the presidential nominee for his support "during his primary (I gave, he won)."

Trump's attack on Ryan comes a day after the House Speaker said that he would not defend or campaign for the Republican presidential nominee anymore following the emergence of a 2005 video that featured Trump bragging about kissing and groping women with television host Billy Bush.

Ryan had said that he would spend the four weeks focusing on how to defeat the Democratic Party and help his party maintain legislative control.

"Paul Ryan is focusing the next month on defeating Democrats, and all Republicans running for office should probably do the same," Ryan's spokesperson Brendan Buck said on Tuesday.

US President Barack Obama's spokesperson had said on Tuesday that Trump's remarks amounted to sexual assault.