Politico suggests that Congressman Raul Grijalva is facing a real challenge from political newcomer Ruth McClung:

Add Rep. Raul Grijalva to the growing list of Democratic worries this election season.

Party operatives say there's increasing concern that the Arizona Democrat's reelection bid could turn into a "sleeper" race for Republicans after Grijalva — responding to enactment of a tough new immigration law — called for an economic boycott of his own state amid a housing crisis and record unemployment.

Four Democratic sources from different parts of the country said that there is new attention to a race that was long considered in the bag.

And a recent poll, obtained by POLITICO, found that Grijalva and Republican challenger Ruth McClung, a real-life rocket scientist, were in a dead heat, even though Washington prognosticators have declared the deep-blue seat safely Democratic.

As they work to buttress their majority against a coming Republican storm, Democrats can ill afford to spend time or resources defending incumbents in seats where they should have a clear advantage. But the Grijalva seat potentially being in play is a sign of the increasingly expanding Republican playing field for the midterm elections.

A recent poll by Magellan Data and Mapping Strategies found that among likely voters Grijalva is leading McClung 40 percent to 38 percent, well within the margin of error of 3.7 percentage points. Thirteen percent of those surveyed were undecided, while 9 percent backed other candidates.

Those results may or may not be an accurate reflection of the state of the campaign. Colorado-based Magellan serves mostly Republican clients and the poll of 686 likely voters on Sept. 29 was an automated telephone poll, generally considered less reliable than those conducted by live callers.