VIRGINIA REPUBLICANS have embarrassed themselves in the unforgiving glare of the national spotlight this winter by muscling through the General Assembly a batch of partisan, incendiary and pointlessly provocative legislation. They’ve enacted bills to thrill the gun lobby (and gun traffickers), delight antiabortion activists and impede voters who lack IDs — mainly Democratic-leaning minority, poor and elderly citizens — based on phony concerns about the nonexistent problem of voting fraud.

Sensing an advantage, Democrats in the state Senate are now striking back with a partisan foray of their own. Using the 20 seats they control in the 40-member upper house, they have blocked passage of the state’s two-year budget and are threatening a government shutdown — unprecedented in Richmond in modern times — unless Republicans redress what Democrats think is a skewed balance of power. Specifically, they want Senate committees, where real legislative power often resides, to reflect the body’s even split between Democrats and Republicans.

That’s not likely to happen. Like it or not — and Democrats obviously don’t — the Republicans have cemented their control of the Senate with the tie-breaking vote of Lt. Gov. Bill Bolling, a Republican who serves in what has generally been, until this year, the ceremonial role of Senate president. The budget is one of the few areas where Mr. Bolling is barred by the state Constitution from wielding the dispositive vote, so Democrats have seized on it as leverage to exact the power they think is their due.

Maybe it’s inevitable that the prairie fires of partisanship, which have blazed through state houses across the country, would engulf the traditionally genteel capitol in Richmond. Still, the Democrats’ maneuver is overreaching, self-serving and cynical, and it may do the party more harm than good.

The $85 billion budget being held hostage was crafted with the participation of Democrats, who raised no major objections to it at critical junctures. In fact, largely because of Democrats, the Senate version of the budget restores funding for education, health and social services that was cut by Gov. Robert F. McDonnell, a Republican, and by the GOP-dominated House.

Ordinarily, differences in the Senate and House versions of the budget would be hammered out in conference between leaders of the two bodies. In this case, Democrats killed off both versions, including their own, and stalked off the playing field.

The few, flimsy objections Democrats have raised about the budget are a smokescreen. Their real issue is power-sharing: Democrats want it; Republicans won’t give it.

In this instance, the Republicans are right: They have the tie-breaking vote in the person of Mr. Bolling. It’s no surprise that Democrats would like to negate that advantage, but the means to do so are through elections, not the nuclear option of government shutdown. And given Republican overreach, Democrats would be shrewder to stand down and let the GOP continue to lay the groundwork for its own defeat.