Republican presidential nominee Donald Trump speaks to supporters at a rally at Erie Insurance Arena on August 12, 2016 in Erie, Pennsylvania. (AFP photo)
US GOP presidential nominee Donald Trump is in danger of losing his grip on the Republican Party, with fears growing that the New York businessman is heading for a “landslide defeat” to his Democratic rival Hillary Clinton in the November election, experts say.
GOP strategists warn that a defeat this fall could also cost the Republicans their majority status in Congress.
"He's in big trouble right now," GOP strategist Ron Bonjean told The Hill. "If we're at this same point after Labor Day where it looks like we're still spiraling into a black hole, I fully expect you'll start to see resources directed to protecting our majorities in the House and Senate."
In recent weeks, Trump has faced increasing opposition from senior congressional Republicans over his feud with party leaders and missteps on the campaign trail. 
Trump infuriated the party earlier this month by initially refusing to endorse House Speaker Paul Ryan, the highest-ranking Republican in the US, in his reelection bid against an outsider.
The former reality TV star also engaged in a back-and-forth argument with the parents of a Muslim-American soldier who was killed in Iraq, drawing condemnation from Republicans and Democrats alike.
Scores of Republican officials have indicated that they will either sit this election out or cross party lines in November.
Trump’s fundraising is also in trouble as many Republican donors have said they are more likely to contribute to Clinton than their own party’s candidate.
This file photo taken on July 28, 2016 shows Democratic presidential nominee Hillary Clinton on stage with husband former president Bill Clinton on the fourth and final night of the Democratic National Convention at Wells Fargo Center in Philadelphia, Pennsylvania. (AFP photo)
Earlier this month, more than 70 GOP lawmakers and operatives signed a letter demanding the Republican National Committee pull back its funding from Trump’s campaign and direct its resources to protecting Republican majorities in the House and Senate.
GOP strategists say that even if the RNC does not renounce Trump, it could still hurt his campaign by shifting its focus on congressional races.
Republicans warn that Trump has a three-week window to get his campaign back on track or he would face large-scale abandonment by the party.
Meanwhile, disenchanted conservatives have circulated a petition calling for the RNC to hold a special meeting to replace the real estate mogul as the party's presidential nominee.
Party rules allow RNC members to replace a presidential nominee in the event of "death, declination, or otherwise." To convene a meeting to discuss Trump’s ouster, organizers must submit signatures by least 16 RNC members from as many states.