Here's a blanket statement about the New Hampshire Senate race: This is not a a friendly fight. In fact, it's probably one of the least friendly contests of the 2014 cycle.

Former Massachusetts U.S. Senator Scott Brown, left, walks into a crowd of supporters after announcing his plans to run for U.S. Senator in New Hampshire Thursday, April 10, 2014 in Portsmouth, N.H. Brown hopes to unseat U.S. Sen. Jeanne Shaheen, D-N.H. (AP Photo/Jim Cole) Former senator Scott Brown (R-Mass.), left, walks into a crowd of reporters after announcing his plans to run for the Senate, again, this time in New Hampshire. (Jim Cole/AP)

Things started getting tense well before former senator Scott Brown (R-Mass.) even entered the race against Sen. Jeanne Shaheen (D-N.H.).

As Brown was flirting with a bid and made his way through the Granite State, he took swipes at Shaheen in fundraising e-mails and speeches. Democrats, meanwhile, took preemptive aim at Brown. The Senate Majority PAC launched an attack ad in early January, for example.

What's going on in the race at this very moment? Both the Democratic and Republican parties in the state basically suggested Monday the other party's candidate may have run afoul of the law. The state GOP asked the Federal Election Commission to investigate whether the Shaheen campaign is improperly coordinating with Senate Majority PAC, following up on a Post report that the Democrat's campaign appeared to be sending smoke signals to outside groups. To be clear, there's no evidence to suggest anything improper.

WASHINGTON, DC - APRIL 1: U.S. Sen. Jeanne Shaheen (D-NH) speaks during a press conference to urge Congress to pass the Paycheck Fairness Act, on Capitol Hill April 1, 2014 in Washington, DC. The act would ensure equal payment for equal work for both women and men. (Photo by Allison Shelley/Getty Images) WASHINGTON, DC - APRIL 1: U.S. Sen. Jeanne Shaheen (D-NH) speaks during a press conference to urge Congress to pass the Paycheck Fairness Act. (Photo by Allison Shelley/Getty Images)

The state Democratic Party, meanwhile, suggested that Brown "possibly skirted FEC regulations" since he said in a recent interview that he decided to run against Shaheen on Valentine's Day but didn't file with the FEC until later. The party also criticized him for not terminating his contract with Fox News at that time. Like in the above case, there's no evidence of wrongdoing.

Still not convinced this will be a nasty race for the duration? Well take a look at this, then. The Boston Globe reported Monday that when Brown was in the Senate, he and Shaheen had no real working relationship and hardly even spoke to each other. Not only that, aides from both sides used less than flattering terms to describe the other candidate, like "shallow" and "nothing sandwich." So, yeah:

But over three years serving together in the clubby Senate, Republican Scott Brown of Massachusetts and Democrat Jeanne Shaheen of New Hampshire created no bonds — despite their common regional interests and mutual claims of a willingness to work across the aisle — according to interviews with current and former staffers and advisers.

They never argued, true, but they also almost never agreed. Although their signatures appeared on a few of the same letters, and they cosponsored some minor bills (one congratulating the Boston Bruins for winning the 2011 Stanley Cup), that work was performed at the staff level. The two senators rarely interacted and barely spoke.

The unusually cool relationship across the partisan divide helps explain why the New Hampshire Senate race has quickly turned bitter, now that Brown has moved north and is running against the incumbent Shaheen after Elizabeth Warren foiled his own 2012 reelection bid in Massachusetts.

... Current and former Brown advisers say he never had reason to work with Shaheen. One former adviser described Shaheen as “a nothing burger” who “always voted with her party.”

Shaheen’s advisers, meanwhile, say Brown lacked substance and was unwilling to engage in the quiet work necessary to get things done in the Senate. One former adviser referred to Brown as having “very, very shallow depth of understanding or analysis.”

There's also the extended back-and-forth over the so-called "People's Pledge" that upstaged everything else for a period after Brown entered the race. Shaheen has been pushing Brown to renew the pledge he persuaded then-Democratic challenger Elizabeth Warren to sign on to in their 2012 Senate contest in Massachusetts, forswearing contributions from groups outside the state. Brown so far has demurred this round.

Last year, Fix Original Recipe wrote that that the nastiest Senate race of the cycle kicked off when Secretary of State Alison Lundergan Grimes (D) launched her bid against Senate Minority leader Mitch McConnell (R-Ky.). Indeed, that race has already gotten very nasty. And the two sides have not even fully engaged yet, since McConnell has a primary on his hands.

But given how things have gone in New Hampshire, the Brown-Shaheen race should at least be in the conversation for the dubious distinction.