HOUSTON — A former president, George H.W. Bush, endorsed Senator McCain’s bid for the Republican presidential nomination today, saying he has “the right values and the right experience” to lead the country.

Speaking with Mr. McCain at his side in Houston, Mr. Bush said the Arizonan has “character forged in the crucible of war” and called him the right person for the job at a time when America “does not have the luxury of taking a pass” on its responsibilities in an increasingly complex world.

Mr. McCain said he was “deeply honored” to have Mr. Bush’s support, noting that both were naval aviators and that both had been shot down in combat.

President Bush has spoken warmly of Mr. McCain, calling him a “true conservative.” But the younger Mr. Bush also has said that Mr. McCain might have to work harder to win over the support of the Republican Party’s more conservative wing, and the president has not formally endorsed any candidate while there still is a Republican nomination contest.

The former president said today that he did not choose to come out for Mr. McCain in any effort to pressure a former Arkansas governor, Michael Huckabee, to drop his candidacy, saying that it can “take time for any candidate to read the writing on the wall.”

Mr. McCain said he thought the endorsement today was very helpful in his efforts to unite the party.