Quid Pro QuoTHE MORE circumstances emerge about the deal that flipped control of the Virginia state Senate to Republicans, the seamier it looks. And there’s plenty we still don’t know.

To recap: The Senate was under Democratic control until early June when Sen. Phillip P. Puckett, a veteran Democrat from rural southwestern Virginia, suddenly resigned. At the same time, word leaked that a high-ranking job was arranged for Mr. Puckett at the state tobacco commission, which is under Republican control.

The resignation of Mr. Puckett, whose term in office ran until January 2016, left Republicans with a 20-to-19 edge in the upper chamber. Critically, by shifting the power balance in Richmond, Puckett’s resignation dashed Gov. Terry McAuliffe’s (D) hopes of forging a legislative compromise to expand Medicaid under Obamacare and extend health insurance to hundreds of thousands of low-income Virginians.

Now the FBI is looking into just how coupled they might have been. Virginians have a right to know, too. If it turns out that Mr. Puckett was essentially bribed to resign with the promise of a well-paying job — and shift control of the Senate to the GOP in the bargain — that could be a criminal matter.

Republicans denied suggestions that an unseemly quid pro quo had been arranged; so did Mr. Puckett, who quickly removed his name from consideration for the tobacco commission job. He said he was resigning for unspecified family reasons, as well as to clear the way for his daughter to be approved for a state judgeship; by tradition, the Senate does not approve judges who are related to sitting senators.

However, e-mails obtained last week by The Post suggested that the tobacco commission job, whose duties were to be left largely to Mr. Puckett to define, had been in the works for at least 10 days and possibly a good deal longer. The appearance of a conjunction between his resignation and the job offer was so obviously indecorous that the commission’s chief warned the body’s GOP chairman to “decouple” the announcements.