New York ? Third party candidates are shaking up two major races in elections Tuesday, and the success of those candidacies is a warning shot fired at both major parties by voters angry at government and disillusioned by politics as usual.

In New York’s 23rd Congressional district, where longtime Republican Rep. John McHugh stepped down to be Army secretary, Dede Scozzafava, the candidate chosen by state GOP leaders to replace him, was forced out of the race by a surging Conservative Party candidate, Doug Hoffman. High-profile national Republicans endorsed Hoffman, saying Scozzafava, a state assemblywoman who supports abortion rights and gay marriage, had abandoned core GOP values.

In the New Jersey governor’s race, independent Chris Daggett has gone from afterthought to player in a contest pitting the unpopular incumbent, Democrat Jon Corzine, against Republican Chris Christie.

Daggett is not expected to win the New Jersey contest, and the GOP split in upstate New York could throw the race to Democrat Bill Owens.

But the impact of those candidacies on the high-profile contests points to an anti-incumbent, anti-establishment sentiment that could be a prevailing theme in the 2010 congressional elections and beyond.

“What it says is the public is looking for less self-interested parties and candidates who can reflect the needs of a very frustrated public,” said Douglas Astolfi, a history professor at Florida’s St. Leo University. “We have two wars and we’re in a recession that neither party seems to address in any positive way. There’s a deep sense that government has abandoned the common man. People are frustrated and angry.”

Indeed, a Wall Street Journal-NBC News poll released last week found that trust in government is at a 12-year low, and half of all Americans now support the creation of a new political party.

Both parties ignore such sentiment at their peril in 2010 and perhaps into the 2012 presidential race.

In Senate contests from Florida and Kentucky to New Hampshire next year, conservatives furious at the Republican establishment are mounting primary challenges against more mainstream candidates favored by the national party.

On the other side, Democratic strategists worry that progressives, disgusted by the big money bank bailout and disillusioned with President Barack Obama’s lack of fight on issues such as a government-run health insurance plan, might keep some people from voting. That could cost Democrats seats up and down the ballot.

Political operatives are keeping an eye on independent voters — an important and growing group that often decides elections. Will these voters send a signal to politicians Tuesday as well or will they stay home and leave it to the more ideologically driven base voters in both parties?

That was the case in the New York race, where polling found Scozzafava had fallen well behind Hoffman and Owens, making it essentially a two-man contest days ago.

Sensing opportunity, ambitious conservatives across the country have jumped on the Hoffman bandwagon.

John Weingart, associate director of Rutgers University’s Eagleton Institute of Politics, said Daggett’s candidacy had succeeded in giving disillusioned voters a competent and credible alternative to Corzine and Christie.

But Weingart said lack of money, the institutional obstacles to a third party candidacy and a growing awareness among voters of the ideological differences between Christie and Corzine would stall Daggett’s campaign .

In the 1992 presidential race, money wasn’t an issue for billionaire businessman Ross Perot, whose rise was powered by the same kind of populist anger brewing today. Perot vastly altered the dynamic of that contest, running as an independent and winning 19 percent of the vote.

Democrat Bill Clinton was the beneficiary of that three-way contest, taking away the presidency from George H.W. Bush with just a plurality of the vote.