(CNN) - Wisconsin Rep. Paul Ryan, widely viewed as a rising star in the Republican Party and a favorite among conservatives, is endorsing former Florida House Speaker Marco Rubio's bid for the Senate Republican nomination in that state.
"In the coming years, America faces critical decisions on government spending, taxes and entitlements that will require idea-driven leaders," Ryan said in a statement released by the Rubio campaign. "Marco Rubio has proven he is exactly the type of consistent, principled conservative the Republican Party needs to ensure the relationship between the federal government and the individual is one that maximizes freedom and prosperity."
Rubio is running against Gov. Charlie Crist, the early favorite who won the national party's endorsement last summer. But many conservative leaders have never been fond of Crist - considered to be a moderate who backed President Barack Obama's stimulus measure last year - and recent polls suggest Crist's lead over Rubio has narrowed to single digits.
News of the Ryan endorsement comes a day after Florida Republican Party Chairman Jim Greer, appointed by Crist in 2007, resigned his post after being assailed for months by GOP activists who accused Greer of mismanaging party finances and favoring Crist over Rubio in the primary.