Eric Trump criticized Republicans for not "fighting" hard enough as President Trump struggles to advance his agenda.

"My father said it a couple of weeks ago and in a tweet," Eric Trump told Fox News' Sean Hannity on Monday night. "He said, ‘Am I going to have to carry this whole weight on my shoulder? When are some of the people in my own party going to start protecting me?'"

"I want someone to start fighting for him," Eric Trump added. "He is the best fighter in the world. He will do a better job fighting for himself than all of them [Republicans] will do fighting for him. But how much weight does he have to carry by himself?"

Senate Republicans have failed in their attempts to repeal and replace parts of Obamacare. Trump blasted members of his own party in tweets over the past few days, encouraging Republicans to try again and threatening to cut health insurance payments for members of Congress.

Some Republicans, meanwhile, say Trump has not been engaged in the healthcare debate or tried to sell GOP reforms to public.

Eric Trump, the president's second-eldest son, is managing his father's business empire with Donald Trump Jr., the oldest son.

He says Republicans should "get in line" to support his father or risk losing the backing of the president's supporters.

"My father has the voice of this country," Eric Trump said. "The people of this country love him. Why wouldn't they get in line?"