WASHINGTON (CNN) -- California Rep. Duncan Hunter, who is seeking the GOP nomination from president, trumpeted his strong anti-illegal immigration stance Friday and called for the building of a fence along the U.S.-Mexican border during an address to a conservative conference in Washington.

"Ladies and gentlemen, we have today incarcerated in federal, state and local penitentiaries and jails 250,000 criminal aliens," Hunter told the crowd at the Conservative Political Action Conference. "Some of them are so bad that their countries won't take them back, like the M.S. 13 gang-bangers.

"We pay $3 billion a year to incarcerate them. We could save enough money in one year in incarceration costs to build a thousand miles of border fence. Let's build this fence."

Hunter was the first of several 2008 presidential aspirants to address the large crowd of conservative leaders and activists. Former Arkansas Gov. Mike Huckabee, former New York City Mayor Rudy Giuliani, Colorado Rep. Tom Tancredo, Kansas Sen. Sam Brownback and former Massachusetts Gov. Mitt Romney are all slated to speak at the conference later Friday.

Arizona Sen. John McCain opted to skip the event, heading to Utah and Arizona instead.

-- CNN's Alexander Mooney and Bill Tucker