HARRISBURG - The state's plan seemed simple enough: Starting on a holiday weekend and for a few days at most, shut down a computer system used for criminal background checks on gun buyers so important technological upgrades could be made.

But a backlash and an unsuccessful court challenge gave state political leaders a potent lesson about the sensitivities and vigilance of the state's gun-rights supporters - and another reminder of the challenges faced by gun-control advocates in Pennsylvania.

Protests over the planned Labor Day shutdown became so vociferous that Gov. Rendell agreed to reconsider before deciding, for practical and financial reasons, to go ahead with it.

The upgrades took about a day and a half, allowing the system to go back online faster than anticipated, and state officials contritely promised to consult with sportsmen's groups and gun dealers in the future before taking actions that affect them.

It was not the first time this year that a gun issue had proved explosive in Pennsylvania politics. In April, a proposal by Rep. Angel Cruz (D., Phila.) to require gun registration and an annual per-gun fee drew hundreds of angry protesters to a Capitol rally that featured a banner suggesting Cruz should be "hung from the tree of liberty for treasonous acts against the constitution."

And that was for a legislative proposal widely seen as going nowhere.

Gun violence plagues many Pennsylvania cities and has been driving Philadelphia's homicide count, which is nearing 300.

But any effort to address it has to pass muster with the gun lobby, or risk mobilizing the formidable network of its supporters poised to respond at the first hint that Second Amendment rights could be in jeopardy.

Gun ownership is important to many Pennsylvanians, the National Rifle Association has about 250,000 dues-paying members in the state, and last year the state awarded nearly 900,000 "antlerless" deer hunting licenses.

A bill to make gun owners report when their weapons are lost or stolen was voted down this year, with a handful of Democrats helping to defeat it.