All four Democratic candidates for New Jersey's special US Senate election met for the first time in a debate on Monday night, eight days before the state's primary election on August 13. And for a race that shows one candidate, Newark mayor Cory Booker, dominating the rest of the field by double-digit margins, there was a surprising lack of viciousness on display.

The candidates – Booker, veteran congressmen Rush Holt and Frank Pallone, and state assembly speaker Sheila Oliver – are seeking the seat left vacant by the death of 89-year-old Frank Lautenberg in early June.

In a traditionally blue state, the winner of next Tuesday's primary would have the edge over the Republican nominee (most likely businessman and former Bogota, New Jersey, mayor Steve Lonegan.) Polls from July showed Booker commanding approximately half of the Democratic primary vote, with his nearest competitors trailing by dozens of percentage points.

Holt, the PhD scientist representing New Jersey's 12th district, is rolling out a $350,000 ad campaign to run in New York and Philadelphia markets in the last week of the campaign. While the candidates to this point have been unusually hesitant to "go negative" on Booker, Holt's ad attempts to do so – at least as "negative" as a wonky scientist can bring himself to be.

In the ad, Holt, wandering around a classroom, introduces himself as the "scientist who beat the supercomputer in Jeopardy!" He then contrasts his positions on "breaking up the banks" and other issues dear to progressives with those of Booker's, before closing: "Cory may be the frontrunner in this race, but he's no progressive."

Holt, who's made waves in the current surveillance debates by proposing to repeal both the Patriot Act and the 2008 Fisa Amendments Act, echoed his science-and-Jeopardy! credentials in his opening statement. He also took a modest swipe at Booker's national celebrity status: "I should level at the start – I've never run into a burning building, I'm not friends with Mark Zuckerberg."

Booker, Oliver and Pallone all opened by touting their different leadership experiences: Booker, as the mayor who brought "progress" "innovation" and "resources" to the decaying city of Newark; Oliver, who's led the state assembly for four years and served another six before that; and Pallone, who claims to know the way and have the record of getting things done in a sharply divided Congress.

The debate was surprisingly heavy on foreign policy, with extended segments on strained relations with Russia, trade policy with China, and what to do about the Syrian situation. The responses were mostly similar boilerplate on these issues – Assad needs to go (somehow), Russia needs to show more in the way of democracy and respect for human rights, and China needs to stop manipulating its currency. (It was not the strongest area for Oliver, the state assembly speaker, who at one point noted that the Boston-bombing Tsarnaev brothers "emanated from the Soviet Union".)

The lead question, addressed at Holt, was about whether recent terror threat murmurs were changing his mind about the way he views the NSA's surveillance programs. "No," Holt responded, noting that we can "presume these were international intercepts that we should be doing". It's the wholesale collection of personal information of Americans that is "completely unacceptable".

The other candidates followed up by noting that the goal is to balance surveillance with protection for civil liberties, and so on. Pallone, representing New Jersey's sixth district, added that right now, "the balance is skewed too much" towards surveillance. Booker noted that terrorist threats are not "abstract" to him; he's seen buildings in Newark become targets of terrorist investigations and "sat in the White House situation room" with other mayors to discuss counter-terrorism.

Booker even dared to knock Holt and Pallone for voting for the original Patriot Act, even though "now they're trying to throw the whole thing out."

Overall, though, limits for responses – and the studio's lack of an audience to rouse up for reactions – kept the debate a relatively sedate affair without too much friskiness.

Booker underwent his most sustained attack near the end, when his alliance with Republican governor Chris Christie on education reform came up. Pallone noted that Booker has been "very supportive of Christie's education plan", meaning "vouchers", "privatization" and other corporate-backed elements to disrupt traditional forms of public education and weaken teachers' unions.

Oliver added that the state's involvement in Newark's public school system has "not seen improvement", and vouchers have merely "siphoned" money away from public schools. Holt added that a "massive expansion of charter schools is not the answer".

The Newark mayor was able to rebut the criticisms by calling hypocrisy on Pallone and Holt, whom he claimed voted for a similar voucher program for District of Columbia schools.

The candidates will meet for another debate on Thursday. But if it goes anything like tonight's – or even if Booker gets demolished, honestly – next Tuesday's primary is setting up to be the confirmation of a result we already know.