They’re mad as hell and they’re not going to take it anymore.

So they’re marching.

On Saturday, backers of President Trump are planning marches across the country in a show of unity and support for his agenda. In several places, anti-Trump groups are vowing to try to undermine the rallies.

Pro-Trump groups say they are tired of all the attacks on a president who has been in office barely three months.

"Why are we here is because we have a president that has been in office, by the time of the march, what ... 65 days?” asked former Rep. Doreen Costa, a Rhode Island Republican, in a rhetorical question to the Providence Journal.

“All this resistance: 'He's not my president,'" she continued. "News flash: He is. He is everybody's president. I did not vote for Barack Obama, but he was still my president. And you can only resist so much and it's not going to change the outcome of the election.”

The marches, dubbed “Make America Great Again,” or "MAGA,” have met with opposition in some areas, with anti-Trump groups planning to counter-demonstrate.

In Seaside Heights, N.J., Mayor Anthony Vaz, a Trump supporter, said he is determined to have the march in his town despite initial concerns that he and other officials had about potential clashes between pro- and anti-Trump demonstrators.

"It's no secret to anyone that there is a divide in our country right now. ... And when there's a 'pro' (event) there is often a lot of negatives that come with it," Vaz told NJ Advance Media.

“MAGA” organizers in Orange County, Calif., say they expect some 3,000 people at their march. Organizer Jennifer Sterling told the Orange County Register that many of them are expected to women, children and senior citizens.

Sterling said it is to show support for Trump, but also to celebrate patriotism and those in military service.

Anti-Trump groups plan to demonstrate there, too. They say they want to undermine the pro-Trump march.

“We aren’t going to start fights, but we are going to try to stop them from completing their march,” said Byron Lopez, an organizer, who added that he expects about 100 people.