The closing days of the Democratic primary for district attorney in Philadelphia could be mistaken for one of those Three Stooges skits, where fury and frustration foment a slap-fest.

In this version of that scene, Joe Khan and Michael Untermeyer trade blows while other candidates pile on Larry Krasner, who has become the largest single target in Tuesday's election, thanks to the deep pockets of a famous fan.

Khan, a former city and federal prosecutor, was the first candidate to "go negative" with a television ad knocking Untermeyer, a former city and state prosecutor, for running for district attorney in 2009 as a Republican.

Untermeyer drew his own target by investing $1.25 million of his own in the campaign (including $300,000 on Tuesday), which allowed him to be the first candidate to air television commercials seven weeks ago.

Untermeyer took direct aim at Khan in the final week, airing an ad criticizing him for working as an assistant U.S. attorney while President George W. Bush was in office and for taking campaign contributions from defense attorneys.

Khan on Friday said he thought "voters deserved to know" Untermeyer's record as a Republican, including a 2011 campaign for City Council. He acknowledged that he first turned his attention to Untermeyer because he was self-funding.

Untermeyer on Friday said he was just trying to set the record straight about Khan. He called the money he invested in his campaign "a substantial part of my life savings" but would not put a value to his net worth.

His self-funding triggered the so-called millionaire provision of the city's campaign-contribution limits, doubling them to $6,000 for individuals and $23,800 for political action committees.

Those limits don't matter to Philadelphia Justice & Public Safety, an independent political action committee funded by billionaire George Soros to support Krasner. A 2010 U.S. Supreme Court ruling allows such PACs to spend beyond campaign limits if they don't coordinate with a candidate or campaign.

Soros invested $1.45 million to pay for television commercials and canvassers to knock on doors to drum up support for Krasner, a defense attorney who has done civil rights work for Black Lives Matter and Occupy Philadelphia members.

Several candidates, and then a group of 11 former assistant district attorneys in a letter made public Friday, pointed toward Krasner's lack of prosecutorial experience -- something he touts as a positive -- and his work as a defense attorney for people accused of murder and sexual assault.

Krasner's campaign shrugged that off, saying he is running an issues-based campaign focused on reform and noting that all of the candidates are also talking about reforming the office they hope to lead.

Another independent political action committee, Building a Better Pennsylvania Fund, is spending $88,000 in the last week of the campaign to run an ad critical of Krasner. That PAC, funded by building trades unions, has already aired commercials in support of Jack O'Neill, a former assistant district attorney who was a last-minute addition to the primary field.

The question for now, and until the polls close at 8 p.m. on Tuesday, is: Does any of this matter to Philadelphia's Democratic voters?

Elections for district attorney tend to be low on voter turnout. Just 12 percent of the city's voters cast ballots in the 2009 primary and general elections, the last time there was no incumbent running for another term as district attorney.

A poll of 651 likely primary voters, conducted by Khan's campaign Thursday and released Friday, showed him tied with Krasner at 20 percent. Former City Managing Director Rich Negrin ranked at 14 percent, Untermeyer was at 12 percent, former First Assistant District Attorney Tariq El-Shabazz was at 7 percent, and O'Neill and former Municipal Court Judge Teresa Carr Deni were tied for last at 3 percent.

The big winner in that poll: "Undecided" was 22 percent. That leaves the race up for grabs in the closing days of the campaigning.

These types of low-turnout primaries are often called "ward leader elections" because the local party officials and their committee members play a key role in urging voters to cast ballots.

None of the seven Democrats was able to come close to winning support from a majority of the city's 69 Democratic ward leaders, making this an "open primary."

The local party prints sample ballots given to voters by ward leaders and committee people with recommendations on which candidates to support. The party in this race went ward by ward, printing up sample ballots as the individual ward leaders requested for district attorney.

Twenty-six of the 69 wards, including the 34th Ward, led by U.S. Rep. Bob Brady, the city's Democratic Party chairman, opted to leave blank the space on the sample ballot where a recommendation for district attorney would be printed.

Two of the wards, the 21st and the 59th, split their support between two candidates.

Negrin had the most sample-ballot support, with 10 wards, while Untermeyer had 9½, O'Neill had 8½, El-Shabazz had 5¾, Krasner had 4, Khan had 3¼, and Deni had 2.