Rep. Robert Andrews’ 11th hour announcement that he would challenge veteran Sen. Frank Lautenberg (N.J.) in this June’s Democratic primary shouldn’t really come as too much of a shock considering the Congressman’s political history and the depth of his ambition, Garden State Democratic operatives said late last week.

Andrews has run for statewide office once before, has been open about his desire for another shot at higher office, and by all accounts had become impatient with the prospect of waiting to be called up by the powerbrokers who control party politics in New Jersey.

Andrews’ colleagues weren’t surprised that he wants Lautenberg’s seat, but they were surprised that he broke a commitment made earlier this year to back Lautenberg for six more years, one top-level New Jersey Congressional staffer said.

But now that Andrews has bucked the usually tightly controlled party system and put his aspirations on display for all to observe, it will be interesting to see just how far his ambition will take him and how hard the New Jersey Democratic machine will hit back.

Make no mistake, Garden State consultants and Congressional staffers past and present uniformly agree that Andrews faces an uphill battle in his Senate campaign. By Friday his chances were placed somewhere on the spectrum between “slim” and “fighting” with some observers still wondering whether Andrews actually would go through with filing for the Senate race by today’s afternoon deadline.

One senior New Jersey delegation staff member said Friday that “if anybody in this delegation was going to do it it was going to be Rob Andrews … all indications were that he was getting frustrated in the House.”

Although he has a mostly moderate record in the very blue state of New Jersey, Andrews has never had to worry about winning close elections since he won his southwest New Jersey 1st district seat in a special election in 1990.

By the mid-1990s he was seen as a Democratic rising star, and after the 1996 election he announced he would run for governor and initially was favored to win the June 1997 primary. Those plans were thwarted by then-state Sen. Jim McGreevey (D), who by locking down the support of a few influential party bosses in some important northern New Jersey counties, was able to beat Andrews by 2 points in the Democratic primary before he went on to narrowly lose the general election.

A chastened Andrews went back to work in the House, and McGreevey was elected governor in 2001 (though there was some speculation Andrews would challenge McGreevey in the primary that year).

After McGreevey resigned in 2004, Andrews again prepared to throw himself into the gubernatorial race but then stepped back, like a good party foot soldier, to endorse the party leaders’ favored choice, then-Sen. Jon Corzine.

With Corzine’s election as governor in 2005, Andrews’ name was among the pool of House Democrats that were looking for the appointment to the Senate. But Corzine chose then-Rep. Bob Menendez for the seat, much to Andrews’ disappointment. After some speculation as to whether Andrews would challenge Menendez in the 2006 primary, Andrews instead decided to again toe the party line and threw himself into Menendez’s campaign.

Andrews’ next chance for statewide office was to come this year, when many political insiders thought Lautenberg, who just turned 84, would retire. But Lautenberg’s announcement that he would seek another six years appears to have been the breaking point for Andrews.

“His ambition, which is both widely known and which he has not necessarily downplayed or hidden, has sort of rubbed people the wrong way, and it has resulted in opportunities that might otherwise have been his going to other people,” explained a former Congressional aide with ties to New Jersey politics.

“This is it,” said a senior New Jersey delegation staff member. “This is his bite at the apple and when he loses … his ambition is over.”

Andrews admitted last week that he’s the underdog in this campaign. He said in an interview late Thursday that he decided to run “because the people of the state want a change and I want to offer my credentials and my ideas as to what that change is. … I have spent my time listening to people all over the state and they’ve urged me to run because they think we need a change. I think we do, too.”

Andrews declined to talk about how he plans on winning the Democratic primary. But what the 50-year-old Congressman does have going for him is the fact that earlier polling on the race has shown that many voters worry about Lautenberg’s advancing age.

Since his announcement Wednesday evening, Andrews has secured a respectable amount of support in his southern New Jersey base, but he’ll need a lot more help in the northern part of the state — where the majority of Democratic voters reside — if he has any hope of knocking off a party stalwart like Lautenberg.

One key northern New Jersey endorsement that Andrews has on his side is that of Essex County Democratic power broker Steve Adubato. He also has influential state Sen. Raymond Lesniak (D) on his side in the north. But Andrews would be hard-pressed to go endorsement for endorsement with Lautenberg, nor would he be able to go dollar for dollar with the Senator, who at the end of 2007 had nearly $2 million more cash on hand than Andrews.

Perhaps more importantly, the entire New Jersey Democratic Congressional delegation has lined up squarely behind Lautenberg’s re-election bid (though it should be noted that some of those House Members — like Reps. Steven Rothman and Frank Pallone — surely find additional motivation to oppose Andrews because they too have expressed interest in running for Lautenberg’s seat one day).

Gaining any sort of traction in key northern New Jersey counties will be hard for Andrews to do if his colleagues put pressure on their local county parties, as has been the case already in Bergen County, where last week Rothman reportedly headed off an endorsement of Andrews by the county’s party chairman.

“Normally when these things happen they happen so far in advance it’s all the bosses who can flex their muscle,” said the senior Democratic staffer. “What [Andrews has] done now is gotten people in a place where they need to scramble when they didn’t need to scramble. … This is the first time really you’ve seen the delegation flex their muscle.”

And that may put on display some of the uglier parts of New Jersey machine politics that usually are taken care of in backroom deal-making, which party leaders would rather not have on display.

On the national level, several Democratic leaders tried last week to talk Andrews out of making the jump to the Senate battle and creating a race out of what otherwise would have been a coronation.

By Wednesday, numbers from a partially complete Democratic Senatorial Campaign Committee poll began to circulate in New Jersey blogs and other media outlets that showed the playing field to be heavily stacked against Andrews’ bid.

The final results of that poll, which surveyed 517 likely Democratic primary voters Tuesday and Wednesday by the Benenson Strategy Group, showed Lautenberg leading Andrews 52 percent to 21 percent. The poll had a 4.3-point margin of error.

In response to the DSCC releasing that survey, Andrews said he bears no ill will against those who tried to keep him out of the race.

“I think incumbent support programs by majorities and caucuses is exactly the right thing to do,” he said. “I’ve participated in the House and I think it’s their right to do it in the Senate. I have no quarrel whatsoever with the DSCC. … I understand their incumbent protection program. I’m on a different program.”