Democratic presidential candidates, lawmakers, and veterans scrutinized President Donald Trump's lack of military service, following his jeers against Democratic Rep. Seth Moulton of Massachusetts' decision to drop out of the 2020 presidential election.

Moulton, who officially ended his campaign on Friday after months of low polling numbers, said it did not end "the way we had hoped" but added he will be "campaigning [his] ass off for whoever wins our nomination in 2020."

Also on Friday, stocks plunged downward — the Dow Jones Industrial Average closing under 600 points, or 2.4%.

Trump took the two events and combined them into a Twitter taunt against the Moulton.

Democrats contrasted Moulton's tenure in the Marine Corps with Trump's lack of military service.

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Democratic presidential candidates, lawmakers, and veterans scrutinized President Donald Trump's lack of military service, following his jeers against Democratic Rep. Seth Moulton of Massachusetts' decision to drop out of the 2020 presidential election.

Moulton, who officially ended his campaign on Friday after months of low polling numbers, said it did not end "the way we had hoped" but added he will be "campaigning [his] ass off for whoever wins our nomination in 2020."

Also on Friday, stocks plunged downward — the Dow Jones Industrial Average closing under 600 points (a drop of 2.4%). The downwards spiral comes shortly after Trump fueled the trade war against China. The White House announced tariffs on $250 billion worth of imports would be raised from 25% to 30% on October 1, and $300 billion worth of imports that are scheduled to be taxed would also be increased by 5%.

Trump took the two events and combined them into a bizarre Twitter taunt against the Moulton.

"The Dow is down 573 points perhaps on the news that Representative Seth Moulton, whoever that may be, has dropped out of the 2020 Presidential Race," Trump tweeted on Friday.

Read more: 'F--- it. It's the right thing to do': Marine Corps combat veteran and 2020 Democratic presidential candidate Seth Moulton explains why he told his PTS story

Moulton, an outspoken critic of Trump, fired back and said, "I'm glad he thinks that I have more influence over Wall Street than he does," according to Bloomberg News reporter Sahil Kapur. "He's probably thrilled that I'm out."

Moulton's decision to end the campaign was met with grace from other Democratic candidates. Many of them highlighted his military service in the US Marine Corps and numerous awards he received for his deployments to Iraq.

Moulton, a Harvard graduate, became an infantry platoon leader after college and fought in two major battles during the Iraq War. He was awarded the Bronze Star and the Navy and Marine Corps Commendation medal with accompanying "V" devices for valor. His award citations reportedly included "fearlessly [exposing] himself to enemy fire" after four of his Marines were wounded.

"[Seth Moulton] is a real American hero; and I know his service to our country has only begun," former Democratic Rep. Beto O'Rourke of Texas said on Twitter. "Thank you, Congressman, for showing the courage to open up about post-traumatic stress on this campaign — and for all of your leadership."

Read more: Meet the Iraq War veteran and former presidential candidate who wants to carry on John McCain's legacy of public service for a new generation

Mayor Pete Buttigieg and Rep. Seth Moulton at a Democratic gala in Indiana, September 14, 2017. @PeteButtigieg/Twitter

South Bend, Indiana mayor Pete Buttigieg, another Democratic candidate and a former US Navy Reserve officer, also highlighted Moulton's service: "[Seth Moulton] is a patriot who defended our nation and our values as a Marine and as a Congressman," Buttigieg tweeted. "He understands the urgency of this moment, and I'm grateful for his voice and for his service."

Other Democratic candidates contrasted Moulton's tenure in the Marine Corps with Trump's lack of military service.

"[Seth Moulton] served four tours of duty and is a true American patriot," former Democratic Rep. John Delaney of Maryland tweeted in response to Trump. "You are a coward."

Democratic Rep. Tim Ryan of Ohio compared Moulton's military record with Trump's business dealings and insulted the size of his hands.

"Seth Moulton: Seven years in the Marine Corps, Captain Rank, Two Bronze Stars, Navy and Marine Corps Commendation with Valor, Dedicated public servant in the U.S. House," Ryan tweeted.

"Donald Trump: Cameos in 12 films and 14 television series, Failed steak business, Very tiny hands," Ryan added.

Democratic Rep. Ted Lieu of California, an Air Force Reserves colonel, noted Trump's absence during the Vietnam War. Trump received five deferments, including one for a bone spur diagnosis, and was not required to serve. Deferments were not uncommon as the Vietnam War raged in 1960s, but Trump's lack of military service as a 22-year-old, 6 feet 2 inch athlete has raised questions about its legitimacy.

"[Seth Moulton] served in combat & received a bronze star," Lieu tweeted. "You received fake deferments because of your daddy."

"In other words, Rep Moulton remains a hero," he added. "And you remain a frickin coward."