President Barack Obama on Thursday starkly warned Europe's woes could have a "very real" impact on the US economy and meant that it was even more important Congress pass his $447 billion jobs bill.

"Our economy really needs a jolt right now. The problems Europe is having today could have a very real effect on our economy at a time when it's already fragile," Obama told a White House news conference.

"This jobs bill will help guard against another downturn if the situation in Europe gets any worse," Obama said in his first formal news conference since unveiling the jobs plan last month.

"It will boost economic growth, it will put people back to work," he said, noting that the US Senate, where even support from his own Democratic party lawmakers is uncertain, is set to vote on the bill next week.

"I hope every senator thinks long and hard about what is at stake when they cast their vote next week," Obama said.

Obama admitted that US economic growth had slowed this year, but said a combination of production glitches brought on by the Japanese tsunami disaster, the Arab Spring and debt woes were largely to blame.

"There is no doubt that the economy is weaker now than it was at the beginning of the year," Obama said, and argued the jobs bill was insurance against a double-dip recession.

Earlier, Vice President Joe Biden said that euro nations could save their common currency but faced a "wrenching" moment of tough choices needed to stave off global contagion.

Biden was asked at a leadership forum sponsored by the Atlantic media corporation whether the continent could save the euro as a serious debt crisis rages and threatens to spread beyond Europe.

"It can. But this is a wrenching moment that they are going through," Biden said, noting the deeply difficult political choices being faced by European leaders.

"They have got to figure out are they willing to take the risk they need to take to maintain this union? Our belief is they can, and our belief is they will, and our hope is that they will."

But Biden warned that the risk to the global economy from Europe's debt crisis was very real, and noted US pressure on regional leaders to take difficult political choices to stem the crisis.

"I can picture a worst-case scenario in the eurozone that could have an international contagion," Biden said.

Obama has been barnstorming the country stumping for the jobs bill and has furiously singled out leading Republicans, who oppose new stimulus spending and have effectively declared the package dead in Congress.

The row is taking place in the context of the quickening 2012 election campaign and Obama's own plunging approval ratings.

A new Washington Post/ABC News poll this week put his approval rating at 42 percent, a new low, and his disapproval rating at 54 percent, a new high.

Only 37 percent of those asked said they expect Obama to win reelection, a statistic pollsters said was worrying as expectations can drive grassroots enthusiasm for a candidate.

The numbers reflected deep public pessimism over the economy and put into context Obama's downbeat comments on his own prospects for 2012 on Monday, which may have been a calculated attempt to lower expectations.

"I don't mind, I am used to being an underdog," he said in an interview with Yahoo.com and ABC News.