Former President Clinton strategist and CNN commentator James Carville has called on Senator Barack Obama to draft former Vice President Al Gore as running mate in the upcoming U.S. presidential election.

Appearing on the CNN program, "The Situation Room" hosted by Wolf Blitzer, Carville said selecting Gore would send a message that America was "really serious" about environment and energy issues.

"That would send a signal to the world, to American people, to Congress, to everybody, that America's getting serious about this horrendous problem that we face," he said.

Former Vice President Gore has not ruled out a return to politics though has always indicated he would want to return as president.

The mercurial Carville is highly respected within Democratic party circles for his role as chief  political strategist for the successful presidential campaign of then Arkansas  governor Bill Clinton.

Image: James Carville: Credit:  Office of James Carville

Barack Obama today made history as he garnered enough delegates to ensure he wrapped up the marathon Democratic nomination for the presidency.

Image: Sen. Obama campaigning in Des Moines,Iowa. Credit: Joe Crimmings Photography/flickr

The Illinois senator picked up enough delegates from the final two primaries in Montana and South Dakota and gains in superdelegates to give him the win, making him the first African-American to lead his party.

There was no immediate sign of concession from Sen. Hillary Clinton though, who told supporters at a rally that she would be making no decisions on her future tonight.

However she has pledged to "to do what it takes" to get the Democratic nominee in the White House in November, a sign she may be interested in the job as Obama's running mate.

Sen. Obama has described the event as a "defining moment for our nation".

Image: Sen. Clinton in Hampton,NH. Credit: marcn/flickr

As expected, Senator Hillary Clinton romped home in the weekend's Puerto Rico primary by a comfortable two to one margin, reinforcing her strong support among Latino voters. However despite the solid win, it was the weekend's key party decision to seat Florida and Michigan delegates at the Democratic Convention with only half a vote each which appears to have put the final nail in the New York Senator's long and expensive campaign.

Delegates from both Florida and Michigan, states where Sen. Clinton won primaries by a healthy margin, were penalised by the Democratic party for holding their primaries at an earlier date. Originally punished by the stripping of the states' delegates from the convention, the Democratic party's rules committee voted Saturday to allow the delegates won by the nominees to attend the convention in Denver, but under the stipulation that they be given only half a vote each.