Last week's election threw everything up in the air, including President Obama's national security strategy, right? Well, no.

There is a surprising bipartisan consensus on key national security issues that has been obscured lately by election campaigns and political sniping. Turning that consensus into policy will require the president to reach out - and to flex his muscle. It will also require Republicans in the new Congress to demonstrate that they are serious about national security issues.

The first test for both sides will come during the post-election Senate session later this month. The Senate has yet to approve the nuclear-arms reduction treaty Obama and Russian President Dmitry Medvedev signed last April. Dubbed "New START," the treaty would cut both sides' weapons stockpiles by about 30 percent and reestablish a tough verification system allowing U.S. inspectors to monitor Russian nuclear forces.

Presidents Ronald Reagan and George H.W. Bush established these inspections with START I, which was signed in 1991 and ratified by an overwhelming bipartisan majority in the Senate. But the inspections stopped in December, when that treaty lapsed. As of Monday, it will have been 338 days since U.S. inspectors were allowed in Russia.

In July, referring to New START, Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, told Congress, "This treaty has the full support of your uniformed military." Cabinet officials from every administration since Richard Nixon's also gave their support to the treaty during 20 Senate hearings and briefings. The Senate Foreign Relations Committee gave it a bipartisan 14-4 vote of approval. With this level of consensus, Senate passage of New START would seem like a no-brainer.

But senior Republicans led by Sen. Jon Kyl (R., Ariz.) nevertheless delayed action on the treaty. They did so for two reasons: to deny the president a political victory before the election, and to get assurances about extra funding for U.S. nuclear weapons.

Now the election is over, and the president has promised to spend $180 billion on nuclear weapons over the next 10 years - more annually than George W. Bush budgeted. Still, Republicans may procrastinate.

It's up to Obama to force the issue in this early test of how he intends to govern in the wake of GOP gains. He should aggressively and publicly reach out to Republicans, calling them now and meeting with them when they return to Washington. His top officials must speak out about the security consequences of not approving the treaty. And Obama must make it clear that there would be political consequences, too.

It should not be hard. Even for new members of Congress elected with the support of the tea-party movement, it will be tough to appear patriotic while dismissing the military's unanimous advice. Rejecting New START would make them vulnerable to charges that they are playing politics with national security, giving Democrats a foreign-policy issue at a time when Republicans want to focus on domestic matters.

But to press that point, Obama must stay committed to getting the treaty done. As Pentagon spokesman Geoff Morell said last week, "This treaty is absolutely critical to the effectiveness of our nuclear arsenal, our knowledge of Russian nuclear capabilities, and U.S. national security overall. There's no sense in putting off what we need now to the next Congress."

With New START, Washington has a chance to show the American people that the two parties can act together in the best interests of the nation. To make that happen, Obama must demonstrate bipartisanship and strength; one without the other will not work. And Republicans, for their part, have to demonstrate their interest in responsible governance.

If either side of Pennsylvania Avenue misses this opportunity, our national security will suffer.

Joseph Cirincione is the president of Ploughshares Fund and the author of "Bomb Scare: The History and Future of Nuclear Weapons." He will be the keynote speaker at the Nuclear Futures Conference of the Project for Nuclear Awareness, scheduled for 12:30 this afternoon at the Down Town Club in Center City. Anyone interested in attending the free talk should call 215-360-5608.