A high percentage of Republicans consider themselves supporters of the Tea Party and a plurality of Americans believe the groups have been a good thing for politics, a new poll shows.

The NBC/Wall Street Journal poll released Monday evening shows that 71 percent of Republicans consider themselves Tea Party supporters. Forty-two percent of the public believes that the conservative groups have been a good thing for U.S. politics. 

The Tea Party movement -- which sprouted up last year against President Obama's economic policies -- have helped propel several outsider GOP candidates to win their party's nomination in several key Senate races.

Mike Lee of Utah, Christine O'Donnell of Delaware, Sharron Angle of Nevada, Joe Miller of Alaska and Marco Rubio of Florida received the support of Tea Party groups against establishment GOP candidates or incumbent senators.

Democrats and some centrist Republicans have expressed worry that the Tea Party groups, which have a fierce anti-establishment streak, could divide the GOP by demanding ideological purity from political candidates.

But the survey casts doubt on that argument, showing that a considerable majority of Republicans back the activists. It also shows a majority for Republicans in voter enthusiasm measures and a sub-50 percent approval rating for Obama.

Some metrics, however, show that the Democrats' midterm messaging is having an effect on the public.

Fifty-six percent of respondents said that President Obama inherited the poor state of the economy, which is rated the top issue for the election, opposed to 32 percent who say it was a situation for which Obama's policies are responsible.