Reminders of former U.S. President Donald Trump's towering influence over the Republican Party were everywhere at the annual Conservative Political Action Conference this weekend near Washington.

There were kiosks hawking Trump hats and shirts, attendees sporting "Make America Great Again" stickers and even a mock Oval Office where attendees could be photographed next to Trump's picture.

The three-day conference illustrated the iron grip he holds over the right-wing, grassroots base of his party and how hard it could be for a challenger to deny Trump the Republican presidential nomination in 2024.