Republican presidential candidate Mitt Romney is continuing to pull in big endorsements from GOP leadership.

Wisconsin Rep. Paul Ryan announced his support of the former Massachusetts governor Friday. Ryan is chairman of the House Budget Committee.

He said Romney is the best candidate to beat President Barack Obama in November.

"If we drag this thing on through summer, it's going to be harder [to win]," Ryan warned.

Former President George H.W. Bush and Florida Sen. Marco Rubio also endorsed Romney this week.

Pressure from the GOP establishment is growing for the remaining candidates to drop out of the race. So far, Romney holds a substantial delegate lead.

*Originally published on March 30, 2012