TRENTON, N.J. (AP) -- U.S. Sen. Bob Menendez's criminal case instantly became an issue in the New Jersey governor's race when his trial began last week.
As the proceeding started Wednesday, the GOP candidate hoping to succeed Republican Gov. Chris Christie called for Menendez to resign if convicted of fraud and bribery charges in federal court in Newark. A national Republican campaign pressured Democrats to call for Menendez's resignation.
So far, Democratic front-runner Phil Murphy has declined to weigh in on the issue raised by his GOP rival, Lt. Gov. Kim Guadagno, in the Nov. 7 governor's race.
At stake could be a seat in the Senate, a possibility that carries weight because President Donald Trump has struggled to get his agenda through Congress even though both chambers are controlled by his fellow Republicans.
If Menendez is convicted and resigns or is forced out by an unlikely two-thirds majority vote in the Senate before Christie leaves office Jan. 16, Christie would choose Menendez's replacement. But if Menendez's post becomes vacant after that date, Christie's successor would make the pick.
Prosecutors say Menendez accepted lavish gifts, including trips to Paris and a resort in the Dominican Republic, in return for helping Florida eye doctor and friend Salomon Melgen with a multimillion-dollar Medicare dispute and securing visas for his foreign girlfriends.
Menendez said he never "dishonored" his public office, and both men deny any wrongdoing.
Guadagno, who is behind in the polls and in fundraising, seized upon the reasoning by Republicans nationally and jabbed at Murphy after he failed to give a clear-cut answer on whether a possible conviction should lead to resignation. She also introduced an ethics plan that bars public servants from accepting gifts from friends.
Murphy, a former Obama administration ambassador to Germany and Goldman Sachs executive, was asked at a news conference whether a convicted senator should resign, but he declined to answer.
"I've supported and continue to support vigorously Senator Menendez," he said.
He was asked again after the news conference and again declined to answer, but added that he's looking forward to Menendez being exonerated.
"I'm not a lawyer. I'm a big supporter of Senator Menendez, and I think we should see how this plays out. I haven't really thought about it to be honest with you," he said.
Murphy and his wife have donated $18,100 to Menendez's legal defense fund and Senate campaign since the April 2015 indictment.
Guadagno, who is down in the polls by double digits and has served as top deputy to the deeply unpopular Christie for two terms, differed sharply with Murphy.
"If a jury finds him guilty, Senator Menendez owes it to his constituents to step down so that New Jersey can be represented with honor in the U.S. Senate," she said in a statement.
Menendez's senior political adviser, Mike Soliman, called Guadagno's statement "shameful" because she's a former federal prosecutor and should appreciate the presumption of innocence.
Experts say the back-and-forth shows how Murphy and Guadagno are tying each other to unpopular or embattled figures in each party. Murphy regularly links Guadagno to Christie and Trump. Guadagno has tied Murphy to unpopular former Democratic Gov. Jon Corzine, now she's turning to Menendez.
"Both sides are playing guilt by association," said Matthew Hale, a political scientist at Seton Hall University.
The Senate could expel Menendez upon conviction, but that would require 15 Democrats to side with all 52 Republicans to achieve the two-thirds necessary. It's unclear whether Democrats would support expulsion.
Senate Minority Leader Chuck Schumer said Menendez was giving a "spirited defense."
Considering a possible resignation could be an academic exercise since Menendez has shown he plans to fight to the end, Hale said. Menendez lost a series of appeals before the trial began and would likely appeal if convicted.
"I don't think Menendez has any intention of resigning until he exhausts every last possible appeal and they hand him the orange jumpsuit," he said.