(CNN) – In the race for U.S. Senate in Nebraska, Democrat Bob Kerrey received a cross-party endorsement from former senator and Republican Chuck Hagel.
Kerrey is in a heated battle with Republican state Sen. Deb Fischer to replace the retiring Democrat Sen. Ben Nelson.
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The Nebraska Democratic Party announced the former, two-term GOP senator's endorsement Thursday.
In the battle for a majority in the upper chamber, Democrats are vying to maintain control, 53 seats to Republican's 47, but are defending 23 of the 33 seats up for grabs.
The Nebraska race is one to watch as it's become close enough that it has joined others tight races that will determine the party control of the Senate which is hanging in the balance. In the reliably conservative state, Fischer has been considered a favorite in the race but a recent poll indicates a narrowing contest in the Cornhusker State.
A poll released Wednesday from the Omaha World-Herald showed 48% percent of likely voters in Nebraska support Fischer and 45% supported Kerrey, the former governor and U.S. senator from the state. Fischer's advantage is within the survey's sampling error. The last Omaha World-Herald poll showed Fischer up ten points over Kerrey indicating the race may be tightening.
Other indications of a narrowing race include American Crossroads, a Republican super PAC, began running ads Wednesday supporting Fischer, and Fischer's campaign emailed out a release tying Kerrey to Senate majority leader Harry Reid.
For her part, Fischer picked up the endorsement of Republican senator and 2008 presidential nominee John McCain in October. The Republican U.S. Senate hopeful's team announced Wednesday that McCain will campaign with Fischer on Friday.
Vice President Joe Biden lauded Hagel's endorsement while campaigning in Iowa Thursday.
"I spent most of my career as a United States senator, being elected to [the Senate when] 29 years old, working with some great, great – as many great Republicans as Democrats," said Biden pointing to Republicans Colin Powell, the former secretary of state, and Sen. Dick Lugar of Indiana.
"Chuck Hagel of Nebraska," he continued. "Who, by the way, today has gotten on a plane, I spoke to him this morning, flying to Nebraska to help Bob Kerrey, help Bob Kerrey win in Nebraska."
–CNN Political Editor Paul Steinhauser contributed to this report.