The US economy topped the agenda as Republican presidential hopefuls went head-to-head on Thursday.
John McCain's bid was boosted by victory in New Hampshire
In a televised debate before primaries in Michigan and South Carolina, the six rivals agreed the US faced challenges but said they could be overcome.
Iran, US policy in Iraq and Washington politics were also discussed.
The men hope to build momentum before 22 states vote on 5 February - "Super Tuesday"-†for their preferred candidates in the presidential poll.
"We should reduce taxes on middle-income Americans immediately," said Mitt Romney, during the debate in Myrtle Beach, South Carolina.
The former Massachusetts governor, who was born in Michigan, needs a strong result in the state after defeats in Iowa and New Hampshire.
Fred Thompson, the former Tennessee senator, is also struggling to mount a comeback and has said he needs a strong showing in South Carolina on January 19 to keep his campaign alive.
Arizona senator John McCain - who won the New Hampshire primary - said spending cuts were required to get the budget deficit under control.
Former Arkansas governor Mike Huckabee, who won the Iowa poll but finished third in New Hampshire, called for taxes to be frozen ahead of a move to replace income tax with a national sales tax.
Economists warn that the US could fall into recession this year, and national unemployment figures released last week were the worst in five years.
Michigan, which goes to the polls on Tuesday, has been hard-hit by the country's economic woes.
At 14%, Detroit's unemployment exceeds the national average, with at least a third of local people living below the poverty line.
High unemployment is also a major concern in South Carolina. The Republicans hold primaries there on 19 January, the Democrats on 26 January.