President Barack Obama has strongly urged European leaders to prevent their looming debt crisis from dragging down the rest of the world.

He said European leaders must inject capital into the banking system.

"The solutions to these problems are hard, but there are solutions," Obama said at the White House.

Obama also renewed his call for Congress to quickly pass legislation that he says will put construction workers, teachers and others back to work.

The president spoke after several days of difficult turns in his re-election prospects, including last Friday's report that the unemployment rate had risen slightly to 8.2% in May as job creation had slowed, and new signs that the European debt crisis was hurting the US economy.

In the political realm, Wisconsin's Republican governor Scott Walker turned back a recall movement led by organised labour and former president Bill Clinton stirred controversy.

Clinton said Obama should be ready to sign a short-term extension of all expiring tax cuts, including those that apply to the wealthiest taxpayers which the president has vowed not to renew.

In his brief White House news conference Obama also mentioned Greece where elections are taking place on June 17 that could determine whether Athens leaves the eurozone.

He cautioned Greece that withdrawing from the eurozone would mean even greater economic difficulty than the austerity steps already undertaken.

In his opening remarks, Obama stressed the importance of a strong European economy, saying: "If there's less demand for our products in places like Paris or Madrid it could mean less business for manufacturers in places like Pittsburgh or Milwaukee."