Democrats Elaine Marshall and Cal Cunningham both failed to break the 40 percent threshold in the North Carolina Senate primary Tuesday and will now go to a June 22 runoff.

It's a result national Democrats had hoped to avoid. Polls have shown Sen. Richard BurrRichard Mauze BurrOvernight Cybersecurity: Senate Intel releases election security findings | Facebook to meet with officials on Capitol Hill amid Cambridge Analytica fallout | Orbitz admits possible breach Senate Intel releases summary of election security report Overnight Cybersecurity: Trump-linked data firm Cambridge Analytica attracts scrutiny | House passes cyber response team bill | What to know about Russian cyberattacks on energy grid MORE (R-N.C.) is vulnerable and Washington Democrats were hoping Cunningham would emerge from the primary as a strong challenger.

Marshall led Cunningham in Tuesday's unofficial results 37 percent to 27 percent. Attorney Ken Lewis was in third with 17 percent.

While congratulating the candidates, Democratic officials said the primary "energized" the party.

“We would also like to congratulate Ken Lewis, Marcus Williams, Ann Worthy, and Susan Harris, who ran substantive campaigns focused on the issues that matter to voters," state party chairman David Young said in a statement. "Thanks to a competitive primary, Democrats are energized and ready to come together around our eventual nominee."

Cunningham promised to focus on Burr during the runoff campaign.

"I will continue to take the fight directly to Richard Burr and hold him accountable for his 18 votes to ship our jobs overseas," Cunningham said in a statement Tuesday night. "North Carolinians deserve a Senator who will stand with middle-class families, not with the Washington lobbyists with whom Senator Burr is partying tonight."

Still, Marshall is the favorite in the runoff race, according to a survey by Public Policy Polling. Among supporters of Lewis, Williams, Harris and Worthy 51 percent said they'd go for Marshall in a potential runoff, while 27 percent of respondents said they intended to join Cunningham, according to a poll conducted before the primary.

Updated at 11:25 p.m.