Arlington, Va. — Former Rhode Island Gov. Lincoln Chafee entered the race for president Wednesday by calling for the U.S. to switch to the metric system, take an "open-minded approach" to drug trafficking and consider negotiating with Islamic State militants.

With his announcement, Chafee became the biggest longshot among Clinton's rivals, who have a long way to go to avoid becoming historical footnotes in the 2016 campaign.

He did so by casting himself as an anti-war candidate who opposed the invasion of Iraq in 2003, but he quickly detoured into a list of policy proposals that are likely to be non-starters on the campaign trail.

Among them was refusing to rule out talks with Islamic State militants, a violent extremist group that has tortured and beheaded prisoners and opposition fighters as it has overrun parts of Iraq and Syria.

A U.S.-led coalition has launched airstrikes against the extremist group since last August, but Chafee pointed to what he said was the group's protection of antiquities in some of the territory they've taken as a reason to reconsider.

"It's early," he said. "We're coming to grips with who these people are and what they want."

Chafee, a former Republican turned independent who joined the Democratic Party two years ago, has made little effort to set up a competitive campaign operation, beyond a few visits and calls to activists in the early voting states of New Hampshire, Iowa and South Carolina. His launch Wednesday was made during a subdued speech in suburban Washington before a small group that consisted mainly of reporters.

"We must deliberately and carefully extricate ourselves from expensive wars," Chafee told a half-full law school classroom at George Mason University. "We need to be very smart in these voluble times overseas."

Along with moving to the metric system, the policy prescriptions in his speech included ending capital punishment, allowing National Security Agency leaker Edward Snowden back into the U.S. without punishment and repairing relations with Venezuela. His priority would be to end all wars.

"Let's wage peace in this new American century," he said.

Longtime Chafee strategists and donors said earlier they know little about his intentions — or even his rationale for running.

"He's not done anything other than posture on some issues," said Mike Trainor, a former Chafee aide. "The question he's going to have to answer is what credible indications can he give that he is at all ready to run a national campaign."

Clinton has set a goal of raising $100 million for her primary bid. Vermont Sen. Bernie Sanders, who entered the race last week, has said he's already raised at least $4 million. And allies of former Maryland Gov. Martin O'Malley have established a super PAC to support his efforts.

All three have begun building robust campaign operations with staff across the country, a step Chafee has yet to take.

In previous campaigns, Chafee has spent significant sums from his family fortune to further his political ambitions — for example, dropping $1.8 million on his 2010 governor's race. Running for president is significantly more expensive than seeking statewide office, with some pegging the estimated cost of a successful 2016 campaign at more than $1 billion.

Unlike the other Democratic challengers, who've focused on pocketbook issues, Chafee has staked his campaign on growing international instability. His opposition to Clinton, Chafee said, is driven by the belief that the next president should not be someone who supported the war in Iraq. Then a Republican, Chafee was the lone GOP senator to vote in 2002 against the invasion.

Clinton, then a New York senator, voted to authorize the war, which became a major issue during her 2008 campaign. Clinton now opposes putting U.S. soldiers on the ground in Iraq, other than as advisers to the Iraqi forces.

Though he never mentioned Clinton by name Wednesday, Chafee took several veiled swipes at her candidacy, describing the controversies over her family foundation, finances and use of a private email account and server while secretary of state as "regrettable."

"We just can't have that," he said. "We need to just get back the respect and admiration of the international community."

Chafee left the Republican Party in 2007 to become an independent and supported President Barack Obama in both his campaigns. After winning election as governor, Chafee became a Democrat in 2013, but opted against seeking re-election.