San Diego, California(CNN) A federal judge on Monday refused to dismiss the campaign finance violation case against California Republican Rep. Duncan Hunter.

In San Diego federal court, US District Judge Thomas J. Whelan rejected arguments from Hunter's attorneys that the case was politically motivated because two assistant US attorneys attended a fundraiser for Hillary Clinton and later brought the case against Hunter, who was one of the first congressmen to endorse then-candidate Donald Trump during the 2016 campaign.

The judge also tentatively denied a motion to move his September trial to a different venue, despite their arguments that the jury pool in San Diego would be tainted by the ample press coverage of Hunter's alleged misuse of more than $200,000 in campaign funds. The issue will be revisited during jury selection.

Hunter and his wife Margaret were indicted in August on charges that they misused a quarter of a million dollars to furnish a lavish lifestyle between 2010 and 2016 -- at a time when they were repeatedly overdrawing their personal checking account. They were charged with conspiracy, wire fraud, falsifying records and campaign finance violations. The San Diego County congressman's trial is set for September 10.

While Hunter has maintained that the couple's spending on the campaign credit card was an error, his wife has agreed to cooperate with prosecutors. In June she pleaded guilty to conspiring with her husband to "knowingly and willingly" convert campaign funds for personal use.

In the 22-page plea, she acknowledged that the couple spent more than $200,000 in campaign funds for the personal enjoyment of their family and friends, including for family vacations, private school tuition, school lunches and routine household items. Her agreement to cooperate with prosecutors was an ominous development for the congressman, underscoring both the legal and political jeopardy that he is facing.

Hunter, a former Marine who served three tours in Iraq and Afghanistan, maintains that his wife was pressured into cooperating with prosecutors, who he says are politically motivated by the desire to win his district. He has pleaded not guilty and has repaid tens of thousands of dollars to his campaign account, according to Federal Election Commission records.

Hunter's lawyers have sought to get the case dismissed because two assistant US attorneys involved in investigating Hunter attended a Clinton fundraiser in La Jolla in August of 2015 and took a picture with the Democratic candidate, according to correspondence with the Secret Service that was obtained by Hunter's defense team through a Freedom of Information Act request.

Hunter's attorneys said in a pre-trial motion that correspondence between the two attorneys and the Secret Service suggests they pre-arranged a photo with Clinton, and his defense team argued in court documents that "their attendance at the event raises serious concerns regarding a conflict of interest and loss of impartiality."

"The former Acting US Attorney for the Southern District of California and the Assistant US Attorney leading the investigation of Congressman Hunter both attended a political fundraiser for candidate Clinton and shortly thereafter both were involved in initiating an investigation of the first Congressman to endorse candidate Trump. These facts alone warranted recusal" of the two attorneys, Hunter's lawyers wrote in a court filing.

Neither of the assistant US Attorneys donated to Clinton's campaign -- and the US Attorney's office told Hunter's lawyers that they were present at the fundraiser "in their official capacity assisting law enforcement."

In recent court filings, prosecutors also accused Hunter of using campaign funds to carry out five extramarital affairs with lobbyists and aides, including a ski trip.

Hunter has rejected the allegations as a "smear campaign" and Hunter's attorneys said the filing detailing the alleged affairs was intended to "publicly embarrass Mr. Hunter with evidence that reflects poorly on his character."

Hunter, who was elected in 2008, has so far survived the political fallout from the charges, narrowly winning reelection in 2018 against Democrat Ammar Campa-Najjar -- a former Obama Labor Department official who is running against Hunter again in 2020 -- in a deeply Republican district where Trump beat Clinton by 15 points.

Hunter agreed last year to step down from all of his House committee assignments, and has focused recently on a "Justice for Warriors" caucus in Congress that reviews the cases of veterans and current service men and woman who stand accused of crimes in the military justice system.