When Vice President Joe Biden travels to Nashua, N.H., next week, Sen. Jeanne Shaheen won't be with him.

Instead, Shaheen, D-N.H., who faces a competitive challenge this election year from former Massachusetts Sen. Scott Brown, plans to remain in Washington next week for Senate votes and to chair an Appropriations subcommittee hearing, an aide confirmed.

Meanwhile, Republicans have latched on to Biden's trip as an opportunity to call for Shaheen and other New Hampshire Democrats to appear with the vice president and, thus, publicly associate themselves with the Obama administration.

"They should use the vice president's trip as an opportunity to appear with him and personally defend their unwavering support for Obamacare, the president's job-killing tax increases and his radical policies that will increase the cost of energy for the middle class," said Jennifer Horn, chairman of the New Hampshire Republican Party.

As President Obama's approval rating has slipped and his signature health care law has trended more unpopular, vulnerable Democratic Senate candidates have been hesitant to appear at public events with the president. Biden might face a similar rejection as a Democratic surrogate during this midterm election cycle, even though his favorability rating has consistently outpaced the president's.

But Biden might have other, non-Senate-related motives in traveling to Nashua on March 25 for a workforce development event: New Hampshire is an important early primary state in presidential elections, and Biden is rumored to be considering a presidential run in 2016.