The endorsement from former President George Bush is intended to rally Republican support for Senator John McCain.
Mr. Bush says the senator has the right values and experience to guide the nation.
"I believe now is the right time for me to help John in his effort to start building the broad-based coalition it'll take for our conservative values to carry the White House this fall."
Î¾Mr. Bush says McCain has a sound conservative record and yet is not above reaching out to Democrats.
"Part of our Republican creed is a prevailing sense of duty. And in the coming election we do not have the luxury of taking a pass on our unique role and responsibilities in the world. And the indisputable fact that unites the greatest number of Republicans, the most Independents and many good Democrats as well is the fact that noone is better prepared to lead our nation at these trying times than Sen. John McCain."
Senator McCain joined Mr. and Mrs. Bush in a hangar near Hobby Airport.
He says Mr. Bush is viewed with respect and affection by all Republicans and he's proud to have his support.
"There's very few Americans who I know who have served with more honor and dignity and I'm honored to have his support. And President Bush and Barbara, I can assure you that Cindy and I will do everything we can to make sure that you are proud and that your support of our candidacy will be something that you can look back on as having been the right thing to do."
McCain says the effort to unite the party will be enhanced dramatically by this endorsement.
However conservative members of the party gathered to show their continued support for Mike Huckabee.
Dave Welch spoke at the rally organized by Texans for Conservative Principles.
He says Texas Republicans have the right to vote as they choose in the March primary.
"The Texas conservatives are simply saying that we're not going to cow, we're not going to bend, we're not going to yield. We're going to stand.Î¾ It's what Texans do. It's what Texan conservatives do especially, is that we have fought this far too long. There's too much at stake."
Earlier former President Bush told reporters the criticism that McCain is not conservative enough is absurd.
Laurie Johnson. Houston Public Radio News.