(AP Photo/Carolyn Kaster)

President Obama told the PBS NewsHour Monday that in his response to Syria “my intention throughout this process has been to ensure that the blatant use of chemical weapons that we saw doesn’t happen again. If in fact there’s a way to accomplish that diplomatically, that is overwhelmingly my preference.”

At the time, he and his aides were still lobbying members of the House and Senate to provide him with an authorization to use military force against Syria. And it was presumed that the president would use tonight’s speech to the nation to make the argument for that unpopular proposal.

He will speak about the same topic tonight. But with prospects for a diplomatic solition strengthened by a series of dramatic developments Tuesday, he can come at it from a very different perspective.

Instead of talking about the necessity of military intervention, he can talk about the prospect of advancing human rights through diplomacy.

He can admit that this is not easy—acknowledging that he has struggled to get the calculus right. He can explain that there is nothing “soft” about the pursuit of what he has referred to as a “just peace.” He can help Americans to recognize why it is necessary to communicate with, to negotiate with, Syrian leaders whom he and his aides have condemned.

The president’s speech can be instructive. Even, perhaps, hopeful.

He has time for that now.

That’s because Obama has asked for a delay in congressional action on his request. The Washington-insider journal Politico reported Tuesday afternoon that Obama “wants Congress to delay its efforts to vote on authorizing the use of force in response to Syria’s use of chemical weapons until the round of diplomatic efforts that began this week has a chance to play out.”

After the president met with senators Tuesday, Senate majority leader Harry Reid said that, while Obama wants “the credible threat of our doing something about this (chemical weapons) attack…to remain,” he also wants time to have the United States work with France and the United Kingdom, in consultation with Russia and China toward what the White House refers to as “verifiable and enforceable destruction” of Syria’s chemical weapons.

A senior Democrat aide told a reporter shortly after the meeting with Obama, “His main message is we need to allow time for diplomatic situation to play itself out, but at the same time we need to keep the threat of military force credible because that’s how we got here in the first place.”

This is the case Obama can and should make tonight.

Circumstances have, at least for the moment, freed him to focus on his concerns about chemical weapons—which are broadly shared by the American people—without having to make a case for military action. Yes, the president is likely to keep the “credible threat” on the table. But he can also talk about the power and the potential of diplomacy.

He might even quote from a speech he gave almost four years ago.

“The promotion of human rights cannot be about exhortation alone. At times, it must be coupled with painstaking diplomacy. I know that engagement with repressive regimes lacks the satisfying purity of indignation. But I also know that sanctions without outreach—condemnation without discussion—can carry forward only a crippling status quo. No repressive regime can move down a new path unless it has the choice of an open door,” the president said as he accepted the 2009 Nobel Peace Prize.

“In light of the Cultural Revolution’s horrors, Nixon’s meeting with Mao appeared inexcusable—and yet it surely helped set China on a path where millions of its citizens have been lifted from poverty and connected to open societies,” he recalled. “Pope John Paul’s engagement with Poland created space not just for the Catholic Church, but for labor leaders like Lech Walesa. Ronald Reagan’s efforts on arms control and embrace of perestroika not only improved relations with the Soviet Union, but empowered dissidents throughout Eastern Europe. There’s no simple formula here. But we must try as best we can to balance isolation and engagement, pressure and incentives, so that human rights and dignity are advanced over time.”

Obama made an important commitment then.

He can and should renew it tonight.

Read John Nichols on Congress’s role in the Syria debate.