Cal Cunningham, the hand-picked DSCC candidate to face Sen. Richard Burr (R-N.C.), appears to be closing the gap in his primary.

A new Public Policy Polling (D) survey shows the former state senator and Iraq veteran within four points of Secretary of State Elaine Marshall, who leads 20-16. Attorney Kenneth Lewis is at 11 percent.

A month ago, the same pollster had Marshall up 29-12. Marshall's campaign released a poll this week that showed her leading 31-5, but the poll was conducted in February, so it appears Cunningham has gained ground since then.

Cunningham suffers from a lack of name ID and has been stuck in the single-digits in most polling on the race. But Marshall's candidacy does nothing for national Democrats, who fought hard to recruit another candidate for the race.

Marshall has struggled to raise money for the race, so it will be tough for her to hold a lead if things get close. There's also the matter of whether the DSCC needs to get involved (like it did on behalf of now-Oregon Sen. Jeff Merkley in his 2008 primary) to get its preferred candidate through the primary.

(Side note: PPP did a poll for Marshall's campaign this cycle, but the last two polls were both conducted independently.

UPDATE: I should have also noted that PPP president Dean Debnam has contributed to Cunningham's campaign. PPP is a Democratic-leaning firm based in North Carolina, so these ties aren't out-of-the-blue. But they should be noted.)