According to the Richmond Times-Dispatch , Democratic State Senator Phil Puckett (D-Russell) has resigned, shifting the balance of power in the State Senate from a 20-20 tie with LG Ralph Northam breaking the tie to a 20-19 Republican majority.
Congratulations to Senate Majority Leader Tommy Norment for regaining control of the Senate – without an election!
This resignation could not come at a worse time for Governor McAuliffe and Senate Democrats who are anxious to push through the Medicaid expansion before time runs out on the current Commonwealth Budget at the end of June.
This, coupled with the fact that both Senate Minority Leader Dick Saslaw and Senate budget conferee Janet Howell are both on vacation  (and Howell is out of the country), Norment apparently has enough votes to pass a budget over Democratic objections.
Under Virginia Code § 24.2-216, the Governor must issue a writ of election to fill the vacancy when the General Assembly is not in session, and the Senate President pro tempore issues the writ when the Senate is in session.
UPDATE: Bearing Drift has learned that Delegate Ben Chafin (R-Russell) will likely seek the seat vacated by Phil Puckett. Chafin was elected with 98% of the vote in 2013 when he ran unopposed in the 4th House District.