Diane Allen, a Burlington County Republican who has served in the New Jersey Senate for nearly two decades, said Tuesday that she would not seek reelection in November.
Allen, 68, who is socially moderate and fiscally conservative, said that she had hoped to run for another term but that she had "a number of medical concerns that sometimes make it difficult for me to put in the same time and effort I have been able to expend in the past."
Allen was found to have oral cancer in November 2009 but returned to work after six months of treatment.
A former Philadelphia TV news anchor, Allen has represented New Jersey's Seventh Legislative District since 1996. She served one term in the Assembly and has represented the district in the Senate since 1998. The district comprises 17 towns in eastern Burlington County.
In a statement, Gov. Christie praised Allen as "one of the most courageous women and most devoted public servants I have ever known."
"She is a role model for my daughters and should be for any woman seeking to make a positive impact in this world," Christie said.
Democrats are likely to target Allen's seat to try to expand their majority in the Senate, where they hold a 24-16 advantage.
There are about twice as many registered Democrats (64,140) in the district as Republicans (32,612), though 62,538 are unaffiliated with either party, according to state election data.
Both assemblymen who represent the district, Troy Singleton and Herb Conaway, are Democrats. Senate President Stephen Sweeney (D., Gloucester) endorsed Singleton for the Senate seat, saying he had "demonstrated strength and vigor as a labor leader and as a young man who is committed to the needs of working families."
Burlington County GOP chairman Bill Layton couldn't immediately be reached for comment.
Allen said in a statement that "there are those who stand on conviction, who follow their moral compass, and who put people over politics. I look forward to continuing to work with them this coming year."