Presidential rivals John McCain and Barack Obama on Saturday vied for the support of Hispanics, beginning a four-month courtship of a pivotal voting constituency by vowing to revamp immigration policy.

"I come from a border state, my dear friends. I know these issues," McCain told Hispanic elected officials. The Republican senator from Arizona said overhauling the country's broken immigration system, not just securing its borders, "will be my top priority."

Appearing later before the same audience, Obama accused McCain of walking away from comprehensive immigration reform. The Democratic senator from Illinois said: "We must assert our values and reconcile our principles as a nation of immigrants and a nation of laws. That is a priority I will pursue from my very first day."

The two spoke separately to some 700 Hispanics attending the National Association of Latino Elected and Appointed Officials conference. It's the first of three such appearances each is scheduled to make to Hispanic organizations in less than a month, underscoring the importance of the nation's fastest-growing minority group.

Both McCain and Obama were warmly received at NALEO; the crowd gave each standing ovations and cheered loudly. When McCain spoke, the audience shouted down anti-war protesters who interrupted the Republican's speech four times. The audience chanted Obama's name when the Democrat entered later. As he took the stage, Obama said "Si, se puede!" — his "yes we can" campaign slogan in Spanish — and the crowd echoed him.