Democrats have been exorcising some of their most stubborn political demons of late.

In challenging former President George W. Bush over the war in Iraq, they showed they were overcoming their deep post-Vietnam fear of being painted as weak on defense when taking a strong anti-war stance. Now, exhibiting comfort with rolling back Bush-era tax cuts, Democrats seem to be losing their anxiety about the tax-and-spend label.

But there is one issue that retains the power to leave Democrats quivering: gun rights. Gun issues still persistently tie the party in knots and have been used by Republicans to stall two major bills this year, with more likely to come.

“It is a hot-button issue,” said Representative Allen Boyd, Democrat of Florida, a longtime hunter and one of the moderates who typically split from the more liberal wing of the party to support the rights of gun owners. “Some people around here know they can use it as a wedge issue, and they try to do that.”

It is a particularly hot-button topic with veteran Congressional Democrats who believe the party’s strong support for a 1994 assault weapons ban was the real reason they lost control of the House that year  not the House bank scandal, the failed health care initiative, the Contract with America or Newt Gingrich.