Tuesday's upset victory by a Republican congressional candidate in New York City shows that voters are restless.

If Robert Turner's electoral victory Tuesday is a harbinger of things to come, congressional Democrats from coast to coast have to be sweating bullets.

Who is Robert Turner? He's the man who not only should not have been elected to the U.S. House of Representatives from a New York City congressional district, he's the candidate who never should have had even a chance to win.

Democrats have held the 9th District seat since 1923. They hold a 3-1 registration edge over Republicans. Roughly 40 percent of the voting population is Jewish, a group that historically has voted overwhelmingly Democratic.

Further, Turner is a 70-year-old Catholic while his Democratic opponent, 56-year-old David Weprin, is an Orthodox Jew who comes from a storied New York political family.

Yet Turner won, running up a 54 percent to 46 percent margin in a district where he never should have had a chance.

Local factors always are in play in races of this nature. But the overriding issue was President Obama's declining popularity in a district he won by 11 percent in 2008.

Turner ran against Obama while Weprin tried to run away from Obama. Unfortunately, Weprin could run, but not hide, from his party chief.

The congressional seat became open when the longtime Democratic incumbent, U.S. Rep. Anthony Weiner, was forced to resign after a sex scandal. It was expected to stay in the Democratic column.

But polls quickly showed Weprin was in trouble, prompting national Democrats to pour in campaign cash to attack Turner and arrange high-profile endorsements from popular Democrats like former President Clinton. Nothing worked.

Republicans would be wise not to get too carried away by their victory. After all, they lost a special congressional election in New York earlier this year that they were expected to win.

But the Democrats' humiliating defeat Tuesday — there's no other way to describe it — shows that things aren't going Obama's way and that the voters are becoming increasingly restless and irritable. Obama needs to right the ship. If not, he and lots of his fellow Democrats will go down with it in 2012.