Last week in the Virginia Senate, the Republicans steamrolled a redistricting plan through that august body on a strictly partisan vote. What was first proposed as a series of "technical adjustments" to boundary lines for House of Delegates’ districts, was amended without notice to create significant changes in state Senate districts—changes beneficial to Republicans seeking election.

It’s the kind of partisan power grab that can turn the most optimistic voter into a devout cynic. Such actions seem more appropriate for some third-world despot than the men and women of the world’s oldest legislative body in the Western Hemisphere.

The evenly divided chamber took advantage of the absence of Sen. Henry L. Marsh III (D-Richmond), who was attending the presidential inauguration, to push through the vote in the Assembly’s upper chamber. The House of Delegates has yet to act on the measure. The bill would also have to be signed into law by Gov. Bob McDonnel...