Former Rhode Island governor Lincoln Chafee on Thursday announced he will launch a presidential exploratory committee, a surprising move for the Democratic nomination by a veteran public servant who was not previously considered a potential contender.

And he's already indicated that hitting Hillary Clinton on her vote for the Iraq War -- which he opposed -- will be central to his rationale for running, introducing a foreign policy foil to Clinton's cast of potential rivals.

"The 2016 election is an important one for the Democratic Party and for America. Campaigns are the time for debates about the vision for our future and for voters to assess the character and experience of those offering ideas," Chafee said in an announcement video posted on his campaign Web site. "When the Republicans were in power, they left the economy in shambles. Over the last six years President Obama has led admirably. He has revived our economy."

Chafee's announcement brings an unexpected addition to the thin Democratic field, whose few potential candidates have been overshadowed by Clinton’s all-but-certain run. Other Democrats considering a White House bid include former Maryland governor Martin O'Malley, former Virginia senator Jim Webb and Vermont Sen. Bernie Sanders.

The Rhode Island Democrat’s announcement video -- and early comments to reporters -- indicate he may make foreign affairs a cornerstone of his potential bid. While serving in the Senate, Chafee -- who was at the time serving as a Republican -- was the only member of his party to vote against the use of military force in Iraq, a fact he highlights on his website and references in his video. That sets him up as a tough potential critic for Clinton, who was dogged by her support for the Iraq War during the primary fight against then Sen. Barack Obama.

“Americans want safety, stability, and sustainability. We will need fresh ideas and the most skillful diplomacy in dealing with this ever-changing world," he said. "Throughout my career...I exercised good judgment on a wide range of high-pressure decisions...that required level-headedness and careful foresight."

In out-of-the-gate interviews, Chafee has reportedly already argued that Clinton's vote for the war "disqualifies" her from the White House.

The Rhode Island governor served as a Republican member of the U.S. Senate from 1999 to 2007 and left the GOP shortly thereafter. Elected governor of Rhode Island in 2010, Chafee officially registered as a Democrat in 2013. In a surprise move – likely motivated by the prospect of a tough re-election campaign – he chose not to seek another term as governor.

"During the next weeks and months, I look forward to sharing with you my thoughts about the future of our great country" he said at the end of his announcement video.