Retired four-star general Stanley McChrystal endorsed Congressman Seth Moulton for president today, offering a boost to the Massachusetts Democrat’s flagging campaign.

The endorsement came in a joint interview on Thursday with MSNBC’s Andrea Mitchell only one day after Moulton yet again failed to qualify for a presidential primary debate.

The retired general said that he has known Moulton for years and that the endorsement was “as much personal as political,” but insisted that the three-term congressman would make the best president.

McChrystal previously endorsed Moulton in 2014, when the Democrat mounted a successful primary challenge against long-term incumbent John Tierney to win his congressional seat on Massachusetts’s North Shore.

During the interview, Moulton touted the endorsement from “one of the greatest Americans that he has ever known,” and dismissed the fact that he would be yet again excluded from a primary debate. The first two debates required candidates to either reach 1% in three different polls that met the Democratic National Committee’s standards or to have 65,000 unique donors to qualify. Moulton was unable to hit either mark.

McChrystal led U.S. efforts in Afghanistan from 2009-2010 before resigning after making negative comments about the Obama administration in an interview with Rolling Stone. Prior to that, the 35-year-veteran led the Joint Special Operations Command, which oversees elite combat units like Delta Force and Seal Team 6.Moulton has emphasized his foreign policy experience in his campaign. The three-term congressman is a former Marine captain who won a Bronze Star Medal while serving in Iraq.