President Barack Obama tapped San Antonio Mayor Julian Castro as his replacement to head the U.S. Department of Housing and Urban Development and nominated current HUD Secretary Shaun Donovan to lead the Office of Management and Budget during a news conference Friday.

Donovan, 48, has been HUD secretary since January 2009. Castro, a 39-year-old Mexican-American who gave the keynote address at the 2012 Democratic National Convention, has served as mayor of San Antonio, Texas, since 2009.

"Just because you are of modest means does not mean that your aspirations or your opportunity ought to be limited, and it certainly means you can have the talent to succeed and achieve the American Dream," Castro said while accepting the nomination, according to the Associated Press.

Both Donovan and Castro need their nominations to be confirmed by the Senate. Obama urged Congress not to stall on the nomination, calling his nominees “proven leaders” and “proven managers.”

“They are going to be effective and most importantly, they've got huge heart,” the president said.

Obama also praised Donovan, saying HUD has been more efficient since Donovan headed the agency.

"Here's the problem: When you're good at your job, people always want you to do even more," Obama said.

The president also ribbed Donovan about the current HUD secretary’s speech at the news conference.

“It's very rare that an announcement about to OMB gets people choked up. You're really milking that thing, man,” Obama said.”