NEW YORK - Donald Trump declared on Tuesday that he had been freed from “the shackles” of the Republican Party and would now campaign as he saw fit, furthering his split from the party he deemed disloyal to him.

In a series of messages on Twitter, the Republican presidential nominee said House Speaker Paul Ryan, also a Republican, was a “very weak and ineffective leader” who had given his candidacy “zero support.”

The outburst came after the unprecedented defection in recent days of dozens of Republican senators, congressmen and governors over a newly surfaced video from 2005, in which Trump boasts about making unwanted sexual advances toward women.

On Monday, Ryan told his conference he would no longer defend Trump nor campaign with him, and said his goal was to maintain Republican control of the House in November’s general election.

Trump hit back at Ryan, the Republican vice presidential candidate in 2012, who has frequently been critical of him.

In his Tuesday tweets, Trump suggested the defections had made it easier for him to campaign as himself. “It is so nice that the shackles have been taken off me and I can now fight for America the way I want to,” he wrote.

Democratic presidential nominee Hillary Clinton has led Trump in most national opinion polls for months and Trump's poll numbers have begun to drop further since the emergence on Friday's video.  In later tweets, Trump lamented his party’s disloyalty, saying “the Democrats have always proven to be far more loyal to each other than the Republicans!” He added that Republicans were attacking him “from all sides.”

Trump’s declaration of freedom comes amid an unprecedented campaign already marked by insults, accusations and feuds, and makes clear Mr. Trump is ready to amp up his rhetoric and attacks in the final month before Election Day.

The billionaire businessman, in securing the Republican nomination and then later in his campaign to defeat Democratic nominee Hillary Clinton, has gotten into public fights with a federal judge of Mexican heritage; the parents of a soldier killed in Iraq; and a former Miss Universe beauty queen as well as Muslims.

Trump also has made clear that the time to show restraint has passed. Ahead of Sunday’s presidential debate, he hosted a live news event with several women who have previously accused former President Bill Clinton, Mrs. Clinton’s husband, of sexual misconduct.

During the debate itself, he pledged to pursue an investigation of his rival. “I didn’t think I’d say this, but I’m going to say it, and I hate to say it,” before announcing his plan to appoint a special prosecutor to investigate Mrs. Clinton if he is elected president.  Then, at a rally in Wilkes-Barre, Pennsylvania, on Monday, Trump responded to the crowds chants of “Lock her up!” with “Lock her up is right!” In the past, Trump had responded to the chants by saying calmly: “Let’s defeat her in November.”