WASHINGTON (Reuters) - President Barack Obama's use of a rare joint session of Congress to deliver a jobs speech on Thursday reflects a political strategy to try to blame Republicans for an economy at risk of sliding back into recession.

The choice of venue -- the Republican-controlled House of Representatives -- is aimed at sending a clear message to voters that if his plan to reduce high unemployment is blocked by Congress, it is Republicans and not the White House standing in the way of job growth.

With unemployment stubbornly high and most Americans unhappy with his handling of the economy, Obama's speech is part of a 2012 election strategy to shift some of the blame for the struggling economy onto Congress and to portray it as obstructionist.

"It's very important for the president to invoke Congress from the very beginning of this round in the jobs debate," said Jared Bernstein, chief economic adviser to Vice President Joe Biden until April 2011.

"Because if Congress in general, and the House Republicans in particular, block his agenda, he needs to be able to explain to the American people who's standing between them, their jobs, their paychecks and economic opportunities."

Republicans reject the view that they have been obstructionist. They say Obama has spent nearly $1 trillion to try to stimulate the economy but that it has failed to create jobs and instead dramatically increased the national debt.

David Gergen, a political analyst and adviser to four presidents, said using a joint session was "first and foremost an attempt to have Republicans be jointly responsible for the state of the economy."

Gergen, who has advised both Democratic and Republican presidents, said: "He is in effect going into the lion's den and looking at the Republicans in the eye. It's very personal. He wants to say 'I am trying to do something -- are you?' It's a dare. It's a way to shame them."

White House officials have said the speech is being delivered inside the U.S. Capitol because many of the job creation proposals Obama will offer will require the approval of Congress, which controls the purse strings.

White House spokesman Jay Carney said the proposals should get bipartisan support "if members of Congress are serious about trying to help the economy, which we believe is their number one obligation."


Yet Obama's decision to deliver his critical jobs speech to a joint session of the U.S. House and Senate, with all the pomp and ceremony attached to such an event, carries substantial risk if it disappoints or is perceived as being too partisan.

Douglas Holtz-Eakin, a former top adviser to the 2008 Republican presidential nominee John McCain, said he believed Obama was using the venue because "it basically allows him to run against Congress" in next year's presidential election.

But Holtz-Eakin said Obama has a delicate task of delivering a speech in such a high-profile and formal setting that does not appear too political.

He added: "There are a lot of disadvantages in terms of raised expectations. It looks to me like the ratio of hype-to-substance is pretty high here."

Most analysts do not expect the speech to contain any bold new proposals, but instead job-creation measures that have already been debated since the 2008 financial crisis, such as additional tax cuts and infrastructure spending.

Gergen said: "When you ask for a joint session you are diving off a high board -- you've got to deliver. And he runs a real risk of markets sinking the next day."

Barry Bosworth, a veteran fiscal and monetary policy expert at the Brookings Institution think tank, said Obama's choice of venue was "very dangerous if he does something that is perceived as purely political."

"If he does not have a big announcement, if he's not got something more concrete to offer, it will be perceived by a lot of outsiders as an inappropriate use of a joint session."

Presidents rarely call a joint session of Congress. Apart from the annual State of the Union address, the platform is used sparingly.

During eight years in office, Democratic President Bill Clinton called a joint session twice, to deliver speeches on the economy and on healthcare reform, according to the Office of the Clerk of the U.S. House of Representatives.

Republican President George W. Bush used the venue just once -- nine days after the September 11, 2001 terror attacks.

Two years ago, Obama used the platform to push Congress to pass his healthcare plan.

A former Capitol Hill Republican and leadership aide with close ties to the House Republican leadership told Reuters there was already a feeling of cynicism among Republicans about a speech they view as simply recycling old ideas.

"The benefit of a joint session is you are really elevating things to a new level," the former aide said. "But you've set expectations of something new and something bold. If that is not the case even the average American will view this somewhat cynically."

(Editing by Ross Colvin; editing by Mohammad Zargham)