WASHINGTON -- San Joaquin Valley congressional candidate Jose Hernandez flew in space, but his astronaut identity is now under political fire.

In a pointed new challenge, a Sacramento law firm is asking a judge to block Hernandez from describing himself as an "astronaut/scientist/engineer" on the June ballot. The lawsuit notes Hernandez has left NASA.

"Hernandez's attempted use of 'astronaut' violates the Election Code's unambiguous requirement that a candidate's ballot designation reflect one's current profession, vocation, or one held during the previous calendar year," the lawsuit states.

The lawsuit quietly filed Wednesday in Sacramento County Superior Court by the firm Bell, McAndrews & Hiltachk strikes right at the heart of Hernandez's biography. It's a life story he's making considerable use of as he seeks to challenge freshman Rep. Jeff Denham, R-Turlock.

"I went from plowshares to the stars," Hernandez told supporters when he announced his candidacy in Modesto in October.

The French Camp native, born into a farmworker family, trained as an engineer at the University of the Pacific and was selected as an astronaut candidate in May 2004. He flew aboard the shuttle Discovery in 2009 and left NASA in January 2011.

"The challenges our country is facing are far too important to waste any more time on petty partisan political games," Hernandez said Friday.

Independent Chad Condit has also announced his intent to challenge Denham in the redrawn 10th Congressional District, which includes Stanislaus County and the southern portion of San Joaquin County.

Denham's campaign is not publicly affiliated with the legal challenge, though campaign records show the law firm has previously done legal work for the Denham campaign committee. A campaign spokesman could not be reached Friday.

Attorney Charles Bell Jr., one of two lawyers named on the lawsuit, is general counsel to the California Republican Party. The other attorney listed on the lawsuit, Brian Hildreth, has worked for former Republican Gov. Pete Wilson. The attorneys could not be reached for comment late Friday.

The lawsuit cites considerable research into Hernandez's background, akin to that compiled during the course of political campaigns.

The suit notes that Hernandez reported to the clerk of the House of Representatives that he received $150,000 from work as the "executive director for strategic operations" with MEI Technologies.

"In the same disclosure to Congress, [Hernandez] reported that he received no income from NASA in 2011," the lawsuit states, adding that "astronaut is not a title one carries for life."

The California Secretary of State's Office has until Thursday to submit a formal list of candidates, including their job descriptions, for inclusion on the June 5 ballot.