New Jersey Sen. Bob Menendez is in the middle of the roughest patch of a political career that has seen its fair share of tough moments.

New Jersey Sen. Robert Menendez

A series of stories by the Washington Post and the New York Times detailing his connections to Florida eye doctor Salomon Melgen have raised questions about whether the New Jersey Democrat can hang on to his seat. The Times editorial board has called on Senate Democrats to remove Menendez as chairman of the Senate Foreign Relations Committee.

While it seems likely this will get worse for Menendez before it gets better -- the Times piece today is a very tough hit for him -- there is reason to believe that he can survive this episode.

"People are conflating different strands which, so far, seem certainly not to yield anything that isn't survivable, particularly given how hard he will fight," said one senior New Jersey Democratic operative closely monitoring the situation.

Here's the Fix's four reasons why Menendez is still hanging on -- and likely will continue to be able to do so.

1. Quid pro quo. The hardest thing to prove in politics is a quid pro quo. ("Quid pro quo, Clarice?")  Right now the main allegations against Menendez are that he intervened for Melgen in a Medicare dispute and that he played a role in trying to keep the Dominican Republic government from taking over port security, which would have hurt a firm Melgen owned.

Both are serious charges. But, both are also very hard to prove wrongdoing against Menendez.  The Senator has and will continue to say that the reason he intervened in both situations was that he thought it was the right thing to do. And, unless an email or other correspondence between Menendez's office and Melgen (or a top Melgen associate) comes out, it will be impossible to disprove the Senator's assertions of why he acted the way he did.

2. Chris Christie.  Yes, the New Jersey Republican governor is helping Menendez. Why? Because the governor of New Jersey is among the strongest governorships in the country -- it used to be even stronger before the state added a lieutenant governor -- and, therefore, it's what the entire political world in the Garden State cares most about. That goes double when it's an election year in New Jersey and not only Christie but much of the state legislature is up for re-election. (WaPo's Ed O'Keefe detailed this phenomenon in a piece from the state recently.)

The reality is that who New Jersey sends to the U.S. Senate always has mattered less to the state's politicos than who serves as governor and, in truth, who is in the leadership of the state Assembly and state Senate.  That lack of attention/interest works in Menendez's favor at the moment since people in the state still don't seem to be following the story all that closely.

3. 2018. Menendez was re-elected to a second term this past fall with 58.5 percent of the vote and won't be back on the ballot until 2018. That's a massive amount of time in the fast-moving/short memory world of modern politics. While Menendez is clearly in a bad way right now, who's to say where he will stand in two years time?  And, per our point above, if New Jersey voters aren't paying attention now will they remember these incidents come 2015/2016?  It's hard to see that happening.

4. Senate Democrats unified.  Menendez has, so far, received unwavering support from members of the Senate Democratic leadership. (His homestate colleague Frank Lautenberg has been slightly less laudatory.)  Unless and until that united front cracks, and there is no evidence it will any time soon, it's hard to imagine the calls for Menendez to step aside gaining any credence beyond conservative circles.

All of the above goes out the window if there is some sort of smoking gun on Menendez or if the unity that Democrats are now showing in support of him starts to erode.  But, for the moment, Menendez appears to be able to continue hanging on.