Corey Lewandowski is warning Republican lawmakers to get on board with President Donald Trump's agenda or risk defeat in their next election.

Lewandowski, Trump's former campaign manager, explained that it's not just Democrats on Capitol Hill who are roadblocking the president's agenda, but also individuals within his own party.

"President Trump was elected to change the country. And you can get on board that train or you can lose your next election, because - I can promise you this - the Democrats have a different agenda," Lewandowski said.

He argued that Democrats have forgotten about everyday Americans and that's what helped propel Trump to the White House.

"They have forgotten about the middle class, they've forgotten about infrastructure, they've forgotten about the people who voted for Donald Trump for change," Lewandowski said. "And if you don't want to provide that change, in 18 months we're going to have another election."

He warned that if Democrats take control of the House, then it will be impossible for Trump to implement his agenda.

"It's my recommendation to those Republicans in Congress to get on board, get the final conclusion done on the repeal and replace of ObamaCare, get the massive tax cut - the largest tax cut in the history of our country - get that done, get the infrastructure done, get the wall built," Lewandowski said. "If you do those things, you will get reelected. If you don't do those things, it's because you have failed the American people."

Watch more above, and share your reaction in the comments.

'You Aren't Representing Me': Trump Supporter Confronts Maxine Waters

Krauthammer Slams Kathy Griffin: 'Political Pornography from a D-List Comedienne'

Tucker: The Left's 'Diversity Agenda' Is 'Totalitarian, and It Is Everywhere'

Shoving Match, Threats Explode in Texas Capitol Over Illegal Immigration