US Republican front-runner Mitt Romney has come under fire from fellow contenders ahead of Tuesday's primary vote in the state of New Hampshire, - BBC reported.
At a nationally televised debate on Sunday, the former Massachusetts governor's economic programme was called "timid" and his conservative credentials were also questioned.
Mr Romney has a lead over his rivals since his narrow win in Iowa last week.
The winner will challenge President Barack Obama in November's election.
Six candidates remain in the race for the Republican nomination.
Primaries and caucuses will take place in every US state over the next few months before the eventual Republican candidate is crowned at the party convention in August.
But votes in New Hampshire, South Carolina and Florida this month could well shape the race for the nomination.
