Pittsburgh, Pennsylvania: August 30, 2008 -  IR Summary/AFP - John McCain and Barack Obama were supposed to hold rival rallies in the key battleground state of Pennsylvania; on Saturday as the race for the White House has  made stronger with McCain's surprise pick of Alaska's little-known governor, Sarah Palin, as his running mate.

Both campaigns were setting out on tours to introduce their vice-presidential picks to the US heartland: Obama in the wake of his rock-star reception at the Democratic convention and McCain ahead of officially accepting the Republican nomination on Thursday.

The question is how Palin , a 44-year-old with virtually no national political experience who has served less than two years as governor, will measure up against Democratic pick Joe Biden, the Democrats' vice presidential pick, who has spent his much of his 36-year senate career working on foreign policy.

Former Republican presidential candidate Pat Buchanan called the McCain's choice the "biggest political gamble in American political history."

Tapping the self-described "hockey mom" to be the second woman in US history to join a major-party ticket for the presidency was seen as a blatant bid to win over disgruntled supporters of failed Democratic presidential candidate Hillary Clinton.

An avid hunter who opposes abortion, is pressing for drilling in the Arctic National Wildlife Refuge and has a son who will soon be deployed to Iraq, Palin is also favored by the party's conservative grassroots who have been wary of the more centrist McCain.

The influential hardline-conservative radio pundit Rush Limbaugh, once a rabid critic of McCain, called it "an inspired choice" while Tony Perkins, president of the powerful Family Research Council, called Palin "an outspoken advocate for pro-family policies that energize social conservatives."

But while Palin's youth may offset concerns about McCain's age - he turned 72 Friday - it could also destroy one McCain's most powerful weapons against Obama in the run-up to the November 4 elections.

"It clearly makes it more difficult for McCain to criticize Obama's experience," said Professor Tom Baldino of Wilkes University, Pennsylvania.

Obama campaign spokesman Bill Burton blasted the choice and highlighted Palin's lack of foreign policy credentials.

"Today, John McCain put the former mayor of a town of 9,000 with zero foreign policy experience a heartbeat away from the presidency," Burton said in a statement Friday. Full