Feb. 18 (Bloomberg) -- Former President George H.W. Bush endorsed Republican presidential candidate John McCain today, saying he is best prepared to succeed his son and has the ``right values and experience to guide our nation forward.''

``No one is better prepared to lead our nation at these trying times than Senator John McCain,'' the 41st president said at a news conference in Houston as McCain stood at his side.

The former president and McCain said Republicans need to draw on a broad base of voters to keep the White House.

``We as a party must unite and move forward and attract not only members of our own party but independents and so-called Reagan Democrats,'' McCain said.

Bush's endorsement was a demonstration that Republicans are lining up behind Arizona Senator McCain, whose independent stances on some high-profile issues have alienated most factions of his party at times during a 24-year congressional career.

``This is just another sign that the race for the Republican nomination is effectively over and that the party establishment is wrapping their arms around McCain,'' said Charlie Cook, an independent political analyst in Washington.

While McCain, 71, has largely sewn up his party's nomination, some evangelical Christians -- a key Republican constituency -- continue to express reservations about whether he shares their outlook on issues such as judicial appointments.

`Very Helpful'

McCain said Bush's endorsement will be ``very helpful in continuing our effort to unite our party.'' In response to a question about whether influence of the current president, George W. Bush, would affect his candidacy, McCain said he would be ``honored to be anywhere with him under any circumstances.''

Former President Bush, 83, played up McCain's top issue, the Iraq war, in comments seemingly directed at the Democratic contenders who have called for starting to withdraw U.S. troops.

``The United States of America cannot be permitted to falter,'' he said. ``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.''

The former president, who had his own critics among the party's conservative ranks, also touted McCain's credentials. ``His character was forged in the crucible of war. His commitment to America is beyond any doubt,'' Bush said. ``But most importantly, he has the right values and experience to guide our nation forward at this historic moment.''

Differences

Earlier this month, McCain received boos as well as cheers at the annual Conservative Political Action Conference in Washington as he sought to make amends with many of the self- described conservatives upset with him for his initial opposition to the current president's tax cuts, his advocacy of legislation that would have offered illegal immigrants a path to legal status, and his leadership in campaign-finance law overhaul.

McCain's mixed reception at CPAC underscored the challenge he faces as he tries to unify his party.

``I've got a lot of work to do,'' McCain acknowledged while campaigning in Oshkosh, Wisconsin, last week.

The former president wasn't the first member of the family to endorse McCain. Another of his sons, former Florida Governor Jeb Bush, already has done so. And the current President Bush stopped just short of an explicit endorsement, telling CPAC on Feb. 8: ``Soon we'll have a nominee who will carry a conservative banner into this election and beyond.''

Former Massachusetts Governor Mitt Romney quit the race Feb. 7, leaving the field to McCain and former Arkansas Governor Mike Huckabee, who trails far behind McCain. Romney last week endorsed McCain.

Former President Bush said today he had no advice to Huckabee, whom he did not mention by name. ``Let me stress that I had not come here to tell any other candidate what to do,'' Bush said. ``A very wise man once said influence is something you always have until you actually try to exert it.''

To contact the reporter on this story: Edwin Chen in Washington at EChen32@bloomberg.net.

Last Updated: February 18, 2008 11:48 EST