"Mitch McConnell's quiet, principled leadership is key to everything we accomplish on Capitol Hill," Rubio said during the event, according to CNN.
"The way he fought ObamaCare, tooth and nail, and forced the Democrats to use extraordinary measures to pass it was a critical catalyst in electing my entire class of Senate conservatives in 2010. Without Mitch, I don't know that we'd have Senator Rubio, Senator Johnson, Senator Paul or Senator Lee."
Sens. Ron Johnson (R-Okla.), Rand Paul (R-Ky.) and Mike Lee (R-Utah) all have Tea Party support, and affiliating himself with all three will likely help McConnell appeal to those skeptical voters on the right.
McConnell is likely to face a strong challenge from Democrats as well, who believe he is one of the nation's most vulnerable incumbents in 2014. Two Democratic contenders, actress Ashley Judd and Kentucky Secretary of State Alison Lundergan Grimes, have emerged as possible challengers.