City Councilman Richard Thomas defeated four opponents, including incumbent Mayor Ernie Davis in Mount Vernon's mayoral primary Thursday.

Thomas led all candidates with 38 percent of the vote. Davis received 25 percent.

Thomas, 33, spent Friday thanking supporters and rivals from his campaign office on Gramatan Avenue.

He credited his success to a grassroots campaign that secured endorsements from the city's firefighter and police unions, and his appeal is so broad that even Westchester County Republican leaders have lent him support.

"That just validates that 'One Mount Vernon' mantra," Thomas said. "Everybody must come back together and unite as one Mount Vernon."

The 76-year-old Davis, who is also an architect, was seeking his fifth term. He said he will return to his own business when he leaves office. 

"It's the peoples job," Davis said. "It's not mine, and so they decided that my tenure should be over."

Former Mayor Clinton Young, who received just 6 percent of the vote, joined Davis in his campaign headquarters shortly after Thomas declared victory. Both former mayors said that as Democrats, they would support the party candidate. 

The race also included longtime state Sen. Ruth Hassell-Thompson, who received 18 percent of the vote, and veteran city Comptroller Maureen Walker, who had 13 percent.

Other primary votes ousted incumbents around the Hudson Valley.

Another upset came in Putnam County, in the fierce primary battle for district attorney. Incumbent Republican Adam Levy, son of TV's Judge Judy, lost to Putnam Valley Supervisor Bob Tendy.

In the three-way Republican battle for two seats on the Monroe Town Council, voters chose Anthony Cardone and Michael McGinn over incumbent Dennis McWatters.