(CNN) - Expect Sen. Marco Rubio of Florida to follow up on his response to the State of the Union address when he addresses the Conservative Political Action Conference on Thursday, according to a source familiar with his remarks.
And Sen. Rand Paul of Kentucky is also expected to have a big day, as he speaks a week after holding the Senate floor in a nearly 13 hour filibuster.
Rubio, widely considered a potential 2016 presidential candidate, will reiterate "why conservatism and limited government is good for the middle class," the source said.
He won't roll out any new policy positions. While immigration will play a key role in his speech–he'll argue that being conservative means being in favor of legal immigration–it won't be the focus.
Rand Paul is another potential GOP presidential candidate, and his camp is setting expectations high. The Kentucky senator sees the speech as an opportunity to establish himself as a mainstream Republican leader, according to a source familiar with his remarks. Until now, his most ardent following has come from the libertarian wing of the GOP.
The speech follows his filibuster last week of John Brennan nomination's to become CIA director, during which he gained a huge following online for his questioning of the Obama administration's drone program.
His remarks are described as "a uniting speech" which adopt a "a very serious leadership tone." He is trying "to reach out to all flavors of conservatism," the source said.
He will discuss the future of the Republican Party and how to talk about issues in a way that unites all members of the party, including immigration reform and school choice.