President Barack Obama will try to co-opt the anger of Americans stifled by the stagnant economy to punish Republicans at the polls if they kill the jobs plan he unveils Thursday, Democrats said. But even before Obama basks in the pomp of a joint session of Congress to debut the plan at 7 pm (2300 GMT) Republicans are warning that Obama\'s policies on issues like business regulation have been a \"wet blanket\" for the economy. The speech marks a vital moment for Obama\'s presidency, 14 months before he asks voters for a second term, as his approval ratings plumb new depths and polls show the public\'s trust in his economic management is waning. The plan is expected to include infrastructure spending, an extension of a workers payroll tax cut, and other measures designed to convince small businesses to hire new workers and put a dent in 9.1 percent unemployment. The White House says the president is sincere about courting bipartisan support for measures that will quickly create jobs and improve wages for the Middle Class, all while trimming the bulging budget deficit. \"He is very serious about taking measures that are responsible, that have enjoyed bipartisan support, and are the kinds that have direct and quick impact on the economy and on jobs,\" said White House spokesman Jay Carney. But given the dysfunction in Washington, Democrats familiar with the plan say that if it does not make it through Congress, Obama will lambast Republicans for ignoring those trapped in the jobless crisis. Obama believes he has a clear plan, which could total at least $300 billion, to offer urgent and significant relief to the economy amid slowed growth and fractured consumer confidence, the sources said. Then, if Congress has not acted by the end of December, as election year 2012 dawns, he will make a sharp contrast with Republicans whom he will say put politics before their country and ignored a needy economy, the Democrats said. One Democrat with knowledge of the jobs plan said Republicans would have to face voters at the polls next year to answer the question of why they refused to act when the economy was in such trouble. Obama has already said his initiative will include an effort to put construction workers back on the job repairing America\'s creaking infrastructure and an extension of an employee payroll tax cut. Analysts also expect funds to be earmarked for local government, which has been laying off thousands of teachers and other workers, and also an employer tax break to encourage hiring. To counter Republicans who will oppose any extra government programs on principle, the White House is promising expenditures will be offset by cuts in other areas. \"It will be specifically paid for,\" Carney said. Republicans however, empowered by the ultra-conservative Tea Party\'s anti-government crusade, are already mustering against Obama\'s plan as a debate over the very role and function of government in the economy intensifies. They argue that Obama\'s policies are directly to blame for the economy\'s failure to roar back to life after the worst recession since the 1930s. \"We don\'t hold the president responsible for problems that he inherited,\" said Republican Senator Lamar Alexander. \"But we do think he ought to be responsible for making the economy worse by throwing ... a big wet blanket over job creation.\" Republican presidential contender Mitt Romney is also weighing in, describing Obama, whom many Americans still like personally, as out of his depth as the economy stumbles along. \"He\'s not a bad guy, he just doesn\'t have a clue what to do,\" Romney said. Some hopes for bipartisan action were raised on Tuesday when the two top Republicans in the House of Representatives, Speaker John Boehner and Eric Cantor, suggested common ground with Obama on infrastructure, passing trade pacts with Colombia, Panama, and South Korea, and rolling back regulations. But some Capitol Hill observers still believe little of significance is likely to pass the Republican House, and anything that does will be unlikely to significantly impact the economy.