This item has been updated and corrected.

The challenge facing President Obama as he pushes Congress this week to authorize using military force against the Syrian government is perhaps best reflected in two thirty-something lawmakers who once deployed into battle.

They both joined up in the years after the Sept. 11, 2001, terrorist attacks and saw action in Iraq. They're both in their 30s, single, and enjoy budding national profiles.

But Reps. Adam Kinzinger (R-Ill.) and Tulsi Gabbard (D-Hawaii) are at opposite ends of the argument when it comes to Syria. Gabbard represents most of Obama's home state and raised serious doubts about the president's proposed military strikes on Monday. Kinzinger represents part of the state that first sent Obama to Washington and so strongly supports military action that he volunteered to help the White House sell the plan to skeptics.

“The politically popular thing for me to do is just to shut my mouth on this whole thing even if I support it," Kinzinger said in an interview. But when George W. Bush implemented his "surge" strategy in Iraq in 2006, "I was dismayed by the number of people who didn’t support him," he said. "I knew that was the right decision – it probably saved American lives. I determined when I got into Congress that I would never shirk away basically from doing the right thing on international politics.”

Gabbard said that more than a week of reviewing classified evidence, attending hearings and listening to fellow veterans convinced her that there's no need for the United States to engage in Syria. "What you’re seeing from veterans, from all sides, is that we understand that at times war is necessary to fight in the defense of our country," she said. "This is not one of those instances.”

Kinzinger and Gabbard didn't enlist in the military until shortly after Congress authorized military action in Iraq in 2002. Kinzinger, 35, was working for an Internet hardware company when he left to join the Air Force in 2003. He flew missions in Iraq and Afghanistan, was elected to the House in 2010 and still serves as a major in the Air National Guard.

Gabbard, 32, enlisted in 2003 less than a year after being elected to the Hawaii state legislature at age 21. She deployed to Iraq in 2005 as an Army medic and spent time treating the wounded at a camp dubbed "Mortaritaville" because it regularly endured incoming fire. She later served as an aide to Sen. Daniel Akaka (D-Hawaii) and joined the House this year.

The pair are two of the 17 House lawmakers who enlisted or were serving in uniform in the years after the 2001 terrorist attacks, either in combat or support roles in Iraq and Afghanistan. They're among more than 100 lawmakers who are active-duty or retired members of the U.S. military, representing about 20 percent of Congress, according to a Congressional Research Service report. The group reached a generational milestone in June with the death of Sen. Frank Lautenberg (D-N.J.), who was the last veteran of World War II serving on Capitol Hill.

Of the lawmakers who served in Iraq or Afghanistan, just two -- Kinzinger and Tom Cotton (R-Ark.) -- are supporting military action.

Cotton said last week that he supports military action because "we have a vital interest in maintaining the international taboo against chemical weapons" and because U.S. inaction would further destabilize the Middle East.

The other 14 lawmakers, a mix of Democrats and Republicans, are either outright opposed or leaning against committing U.S. military forces.

One of those is Rep. Tammy Duckworth (D-Ill.), who like Gabbard saw combat action in Iraq, but lost both of her legs after a Blackhawk helicopter she was co-piloting was shot and she safely landed it. Duckworth, who now uses a wheelchair, told reporters Monday that she is skeptical of military action in Syria.

"I've heard the discussion before that this type of thing is going to be a limited attack and it will be done in a short amount of time," she said. "War is messy; war is never that simple."

Duckworth said some of her views on the Syria situation are drawn from recent conversations with her fellow veterans. She declined to discuss specifics from those conversations but said that "you need to have those checks from your buddies who'll call B.S. on you, and I've reached out to them."

Rep. Duncan Hunter (R-Calif.), who served in the Battle of Fallujah in Iraq in 2004, is also opposed to the current Syria resolution under consideration in the Senate -- because he believes it doesn't go far enough.

"We need to do it 100 percent, full throttle with no rules of engagement that hurt our guys," Hunter said in an interview last week. "We need to be all-out: It has to be total war. Even if we do a limited strike, it needs to be 100 percent, hitting them as hard and as fast and as powerfully as we can."

Gabbard and Kinzinger said they also drew on their experiences as veterans in making their decisions.

"Obviously we view this through the prism of our own experiences of having served and understanding both the cost of war, but also the incredible sacrifice that our service members volunteer for when they offer to serve our country," she said. "They know what they’re signing up for, to defend our country, defend our Constitution. Understanding that and understanding that a vote for this means sending my brothers and sisters into combat at some point or another and understanding what they have put on the line.”

Kinzinger said his military service "gives me more courage to do the right thing, because I know we’re capable of doing it. Those that haven’t served I think have a level of guilt to send people to combat if they haven’t themselves. I understand that. But since I have served, I can make an educated decision to agree to send people."

And what has Kinzinger been telling those other lawmakers who feel guilty about sending young Americans into war?

"I just say look, as someone who has served, you just have to do the right thing and know that everyone who’s either pushing a button or flying a plane raised their hand and decided to do it," Kinzinger said.

Here's a full review of where the 16 Iraq and Afghanistan veterans in Congress stand on the issue of military action in Syria, according to a Washington Post Whip Count as of Monday evening:

SUPPORTIVE OF MILITARY ACTION: Reps. Adam Kinzinger (R-Ill.), Tom Cotton (R-Ark.)

OPPOSED TO MILITARY ACTION: Reps. Tulsi Gabbard (D-Hawaii), Tim Walz (D-Minn.), Kerry Bentivolio (R-Mich.), Ron DeSantis (R-Fla.), Chris Gibson (R-N.Y.), Tim Griffin (R-Ark.), Joe Heck (R-Nev.), Tammy Duckworth (D-Ill.), Steve Stivers (R-Ohio).

LEANING AGAINST MILITARY ACTION: Reps. James Bridenstein (R-Okla.), Doug Collins (R-Ga.), Mike Coffman (R-Colo.), Rep. Duncan Hunter (R-Calif.).

UNDECIDED: Reps. Brad Wenstrup (R-Ohio), Scott Perry (R-Pa.).

Follow Ed O'Keefe on Twitter: @edatpost

This post has been updated to reflect that Rep. Tulsi Gabbard had previously worked for Sen. Daniel Akaka (D-Hawaii), not the late Sen. Daniel K. Inouye (D-Hawaii). Also, the year of the Sept. 11 terrorist attacks has been corrected.