Romney Ryan VP

AP

Rep. Paul Ryan (R-Wis.) has submitted paperwork to the Romney campaign and is officially being vetted for the vice presidential nomination, National Review reported late Friday afternoon.

Citing unnamed sources, writer Robert Costa said he was “reliably informed” of the development with the House Budget Committee chair.

Ryan endorsed Romney earlier this year and has repeatedly joined him on the campaign stump. Ryan’s camp declined to shed any light on the revelation, telling National Review, “Respecting their campaign’s internal process, we’re not going to comment.”

Though the Romney campaign has been tight-lipped about the possibilities for his No. 2 spot, the former Massachusetts governor admitted this week that Florida Sen. Marco Rubio is being “thoroughly vetted” after reports circulated that he was not under consideration.