A judge will hear arguments Monday about whether he should throw out the federal corruption charges against former Virginia governor Robert F. McDonnell (R) and his wife — or at least separate their cases.

The hearing in federal district court in Richmond is perhaps the most significant yet for the couple, as their attorneys will try to persuade Judge James R. Spencer to dismantle the prosecutor’s case long before a jury hears it.

Though experts say it is unlikely, Spencer could dismiss the corruption counts if he agrees with defense attorneys’ contention that the McDonnells neither promised nor performed any “official acts” for Jonnie R. Williams Sr., the Richmond area businessman who is said to have lavished them with gifts and loans in exchange for their help.

Spencer also could order Robert and Maureen McDonnell to be tried separately — as their attorneys have requested — and put prosecutors at a strategic disadvantage.

The McDonnells were charged earlier this year in a 14-count indictment that alleges they lent the prestige of the governor’s office to Williams and a company he used to run, Star Scientific, in exchange for his largess. They have pleaded not guilty, and a jury trial is scheduled for July 28.

The arguments from both sides Monday probably will come as no surprise to Spencer, as he has been considering written filings about the disputes since March.

The McDonnells’ defense attorneys have contended that the actions the McDonnells are accused of taking for Williams and Star — including arranging meetings between Williams and state officials and promoting Star’s products — are not “official.” Prosecutors must prove that the McDonnells either promised to perform or performed “official” acts to substantiate the corruption charges.

“Returning a supporter’s phone call, asking a subordinate to meet with a supporter, attending a supporter’s event, inviting a supporter to a reception, or saying nice things about a supporter are not ‘official acts’ — even if they enhance that supporter’s actual or perceived stature — because none of those actions deploy the sovereign power of government,” the McDonnells’ defense attorneys wrote in a court filing.

Prosecutors have countered that the acts the McDonnells took for Williams were official, even if they were not particularly substantial. Prosecutors also have argued that at this stage, Spencer need only determine whether they are alleging official actions were taken, and jurors could determine at trial whether they had proven those allegations.

Even if Spencer dismisses the corruption counts and an obstruction charge against Maureen McDonnell, the couple still would face charges stemming from false information prosecutors say they put on financial documents. The McDonnells have disputed those charges, but did not formally move to have them dismissed.

And if Spencer allows any of the charges to move forward, he still could deal a blow to prosecutors by granting the couple’s request for separate trials. Their defense attorneys have argued he should do so because of concerns about marital privilege and the McDonnells’ right not to incriminate themselves.

Only at separate trials, they have argued, would Maureen McDonnell agree to testify — without fear of incriminating herself — that her husband was largely unaware of her dealings with Williams. And only at separate trials, they have argued, would Robert McDonnell be able to testify on his own behalf without his wife silencing him through marital privilege.

Prosecutors have resisted that effort, too, noting there is “a strong presumption in favor of trying defendants together who have been indicted together” and questioning why Maureen McDonnell would not testify at a single proceeding. The bid to sever was dealt a blow, too, when Spencer ruled that the McDonnells’ attorneys could not keep hidden from prosecutors declarations detailing their clients’ prospective testimony at separate proceedings.

The attorneys elected not to file the declarations, which they had hoped would support their arguments, as part of the case. They have, however, indicated they would file the declarations under seal and to the judge only for appeal purposes. Neither Spencer nor prosecutors will review that filing.

Though Spencer could issue rulings right away — as he did at an earlier motions hearing in the case — he could also take time with what he hears Monday before he makes any decisions. The hearing is scheduled for 10 a.m.