Bill Clinton leapt to his wife’s defence yesterday after Barack Obama, her leading rival for the Democratic presidential nomination, said that she had the wrong kind of experience to lead America.

Mr Obama slighted Hillary Clinton by saying that she had “worked the system” when First Lady and subsequently as a New York senator.

Implying that she is nothing more than a cynical political insider, Mr Obama said that America did not need “the kind of experience that tinkers around the edges instead of doing something fundamental” to tackle the country’s problems.

Speaking to This Week, an ABC programme, Mr Clinton accused Democratic rivals who criticised his wife of “rewarding the Republican attack machine” that had “beaten up on her for 16 years”. Mr Clinton’s response ended a weekend in which both men openly attacked each other in a new proxy war to shape voters’ perceptions of Mrs Clinton and whether she or Mr Obama has the best experience for the presidency.

Mr Clinton, in the most aggressive intervention of his wife’s campaign, began the hard-edged exchange on Saturday when he said that Mr Obama was too inexperienced to tackle America’s challenges abroad.

Asked about his own experience when he became President aged 46 - the same age as Mr Obama is now - Mr Clinton said that in contrast to 1992, “we didn’t have the terror threat. We didn’t have the troops in Iraq.

What America needs in a president changes from time to time. Her experience is more relevant and more compelling”.

Mr Obama responded by throwing Mr Clinton’s own words back at him from a presidential debate 16 years ago, when he made remarks aimed at the first President Bush. “You can have the right kind of experience and the wrong kind of experience,” Mr Clinton said at the time.

Mr Obama said at a rally in New Hampshire: “He’s exactly right.” Referring to his own opposition to the Iraq war before the US-led invasion, compared to Mrs Clinton’s vote authorising it, Mr Obama added: “What we need to do is put an end to the wrong kind of experience.”

The question of experience has become the fundamental issue between Mrs Clinton and Mr Obama. Mrs Clinton’s strategy has been to paint her rival, only in his third year in the Senate, as too unseasoned to lead. Mr Obama has responded by confronting the issue head on, a response aides to Mrs Clinton believe plays into her hands.

How they compare . . .

Clinton 1992:

Age on polling day: 46
Position: Governor of Arkansas
Claim to fame: Driving force behind new Democratic centrist ideology

Obama 2008:

Age on polling day: 47
Position: Senator of Illinois
Claim to fame: Opposed the invasion of Iraq before it happened

Times Recommends

• Please help: maimed children of war want their lives back
• Cabal seizes diamond riches to buy power
• White House gatecrashers got to the president