Then-Sen. Hillary Rodham Clinton (D-N.Y.) receives a tour through the barracks of the 2nd battalion, 2nd Airborne Division in Baghdad, Iraq on Nov. 28, 2003. (Dusan Vranic/AFP/Getty Images)

Hillary Rodham Clinton was a senator from New York the last time Congress was asked to authorize military action in the Middle East. Friends think her vote in 2002 to give President George W. Bush the go-ahead to invade Iraq may have cost her the Democratic nomination — and with it the presidency — in 2008.

Today, she is a former secretary of state with another possible presidential campaign in her future. As President Obama ramps up efforts to persuade Congress to authorize military action against Syria, the question is whether this episode will become an asset or a liability if she runs again.

Clinton has not spoken publicly about the chemical weapons attack that Obama administration officials say was launched by Syrian President Bashar al-Assad’s regime, although a Clinton aide issued a statement Tuesday saying that she is behind Obama.

“Secretary Clinton supports the president’s effort to enlist the Congress in pursuing a strong and targeted response to the Assad regime’s horrific use of chemical weapons,” the statement said.

Her 2002 Iraq vote seemed relatively safe at the time but was later fraught with political implications. One Democrat called it “the most politically significant vote case in the history of the Senate,” arguing that without it, Obama’s campaign for the White House might never have gained enough traction to defeat Clinton for the Democratic nomination.

Clinton allies see little comparison between what happened then and the possible fallout for her with the debate about Syria. The 2002 debate, they argue, was ultimately about launching a full-fledged invasion of Iraq. What Obama is calling for, as he reiterated at the beginning of a meeting with congressional leaders Tuesday, is many steps short of that.

History and practical politics underscore why Clinton would embrace the president on this mission. As a member of the administration, she often took a more hawkish line than Obama in pushing for greater military and other support for the Syrian rebels — although like the president and others, she opposed putting boots on the ground as part of that effort. As one former administration official said, “While she understood the risks of a more active engagement, at the end of the day, she was persuaded that we had to weigh in more heavily on the side of the opposition.”

Her allies see no particular political downside to embracing Obama as he tries to gain support for military action. At the same time, they know she has little choice other than to back the president fully, given her past role in the administration.

What isn’t clear is how active or assertive Clinton will be in public as Congress debates whether to give Obama the authority he is requesting. She will have public appearances early next week — one at the White House unrelated to the current debate and a second at the National Constitution Center in Philadelphia, which is part of a series of policy speeches she will be giving this fall. The Philadelphia setting could provide a forum for her to address the Syrian issue and the president’s request for congressional support to launch strikes, if she has not done so earlier.

John F. Kerry, Clinton’s successor as secretary of state, has been the administration’s leading voice on responding to the alleged chemical weapons attack. White House officials are recruiting former officials from this and past administrations to help make the case for military action and to round up votes on Capitol Hill. Former defense secretary Leon E. Panetta has agreed to call members of Congress, and a Clinton aide suggested that she is prepared to do whatever may be asked of her.

One former administration official, who spoke before Clinton’s office issued its statement, recommended that she stay out of the matter, in part because the media will parse and magnify whatever she says.

“Giving the president and Congress the room to decide this issue without her suddenly jumping into the middle of it is probably the right course of action,” said the official, who spoke on the condition of anonymity to be candid. “There will be time to say [what she thinks is] the right course. . . . I think it’s better now to leave it to the president and to the Congress.”

Clinton allies doubt that her support for targeted military action against Syria will boomerang, as her 2002 vote did. And they don’t see any strong opponent on the party’s left flank who could make the case against her, should things turn sour, as they did in Iraq. “That was her vote before,” a Clinton ally said of the vote on Iraq in 2002. “This is going to be [Obama’s] thing, for good or bad.”

Still, as a former member of the administration, Clinton is not exactly a free agent. If she thinks the administration should have taken a more aggressive posture earlier, she is likely to be restrained from saying so, lest she appear disloyal.

Sen. John McCain (R-Ariz.) has the freedom to be both critical of past decisions by the president and supportive of taking action now. Clinton cannot. Almost anything she says about Syria will draw a huge amount of attention, particularly if she were to put any distance between her position and the president’s.

If Clinton runs again, she will be asked for a fuller accounting of her views on Syria and may be pressed to outline where she and the president diverged on what to do. For now, she may choose simply to endorse Obama’s efforts.

In 2002, she helped enable a president of another party, although with the backing of public opinion, and paid a huge price. This time, she is aligned with a president she served, but at odds with public opinion, on the advisability of launching a strike against Syria. This may be Obama’s military intervention, but if she is a candidate in 2016, Clinton may share in whatever credit or blame the public assigns to his decisions.