Today in Lausanne the United States and its partners achieved a major breakthrough in talks to prevent an Iranian nuclear bomb. Both sides were able to agree on key principles that will—if the talks succeed—keep Iran’s nuclear program exclusively peaceful and under the watchful eye of international inspectors. This is by far the most promising path to resolving this crisis peacefully.

"Today, after many months of tough, principled diplomacy, we have achieved the framework" for a nuclear deal with Iran, U.S. President Barack Obama said at the White House. "And it is a good deal."

The progress made in Lausanne by the United States, Great Britain, France, Germany, Russia, and China is the surest sign yet that the 18-month-old talks with Iran can reach a successful final agreement that will enhance the security of all. The parties agreed to significantly limit Iran’s uranium enrichment, redesign the Arak reactor, limit Iran’s nuclear research and development, and strengthen international inspections in exchange for sanctions relief.

But the negotiations have not crossed the goal line yet. The next three months will determine if the parties can seal the deal by the end of June, and many speed bumps remain.

The stakes could not be higher. If the talks fail, the alternatives are “wildly unattractive,” former George W. Bush administration official Richard Haass told CNN. Yet many in the U.S. Congress are eager to kill the talks, presumably under the mistaken impression that a better deal is possible if the Obama administration just takes a harder line. In reality, torpedoing the talks with rash congressional action would make it more likely that Iran would accelerate its now-frozen nuclear program, international sanctions would unravel, and pressure to use U.S. military force would rise.

“People in Congress who root for the deal to fail have not thought through the alternatives, which are stark: The Iranian program will be limited diplomatically, or we will have a war,” said Major General (ret.) Paul Eaton, a former U.S. military commander in Iraq.

There is no reason to risk military action, which is not in the interests of the United States, its allies, or its partners in the region—including Israel. Iran’s nuclear program has been frozen and rolled back over the past year, and strong sanctions remain in place. Time is on our side, so let’s use it. Here’s how:

1. Keep Calm and Keep Talking

The first step to a good deal is to realize that there is no significant downside to waiting a few more months to conclude one.

Critics may argue that Iran will use additional negotiating time to get closer to a bomb.

But that possibility was foreclosed by the interim deal agreed to in November 2013. That agreement, the Joint Plan of Action, required Iran to dilute its most worrisome nuclear materials (uranium enriched to 20 percent U-235, which is dangerously close to what is needed to make a bomb) and keep the rest of its program in neutral. Thanks to more intrusive inspections, international monitors have confirmed that Iran is honoring its commitments. The interim deal is working, and will stay in force until June 30.

As a result, in the past year, Tehran has moved away from a bomb, not closer to one, in exchange for limited sanctions relief. Extending the status quo means this trend will continue. This is a much better outcome than having the talks collapse.

The interim deal is good for now, but we still need a long-term agreement that further limits how large a nuclear program Tehran can have, how much nuclear material it can produce, and what kind of activities it can conduct. This is well worth a few more months of talks.

The public agrees. A clear majority of Americans supports a nuclear deal with Iran, according to the Washington Post.

2.Congress: Keep Your Powder Dry

Despite this public support, Republicans in Congress are trying to derail the talks before they arrive at the station—and before we know the details. Congressional Democrats must not allow this to happen, and they have the power to stop it.

Just look at the March letter 47 GOP senators sent to Iran, which, by warning that Congress could change the terms of the agreement “at any time,” was clearly meant to scuttle the negotiations.

Indeed, Sen. Tom Cotton (R-Ark.), who organized the letter, has said that he wants the talks to fail. “The best solution is walk away from the nuclear negotiations now and return to a position of strength,” Cotton said in March 31 statement.

Sen. John McCain (R-Ariz.) even encouraged Israel to “go rogue” on Iran, presumably meaning that it should launch a military attack.

Now, many senators—including some Democrats—want a mid-April vote on legislation, known as the Corker bill, to approve a process to hold another vote to approve or reject a deal once it is done. Sound redundant? That’s because it is. There is no reason for the Senate to vote to give itself the right to vote later. Congress can vote later anyway.

“We don`t need to pass a bill telling us that we have the power to approve or disapprove a deal once it`s signed,” Sen. Chris Murphy (D-Conn.) told MSNBC on March 31. “We should just have the good sense and the maturity to wait and let these negotiations play out so that we can look at an agreement and decide whether we want to move forward on it with an up-or-down vote.”

The only reason to hold a vote in April—on either the Coker bill or a separate bill to add new sanctions—is, like the 47 senators letter, to undermine the deal. It would send the same message to Iran: Congress is waiting to kill any deal that might come along.

Drafted by Sen. Bob Corker (R-Tenn.), this bill would give Congress 65 days to review the Iran deal and then vote. Even if Republicans were not already predisposed to reject it, this is not enough time to review the complicated details or to determine if Iran is living up to its commitments. It’s a recipe for rejection.

Yet Congress does have an important role to play here. Congress approved the sanctions that have brought Iran to the bargaining table, and Congress must vote to remove those sanctions. But it makes more sense to have that vote after Iran shows it has met its obligations. Better to have President Obama waive the sanctions temporarily so they can be easily “snapped” back if needed.

Similarly, the United Nations must vote to remove its sanctions. But unlike President Obama, the UN does not have waiver authority.

With their ill-advised letter to Tehran, GOP senators have shown that they cannot rise above partisan politics on Iran. Thus it should come as no surprise that the White House wrote to Sen. Corker on March 14 with a simple request: “Let us complete the negotiations before the Congress acts on legislation.” Why? Because a congressional vote now on Corker’s bill “would potentially prevent any deal from succeeding.”

Let’s be clear. A vote on the Corker bill before the deal is done is a vote to kill the deal. This simple fact often gets lost in the tortured debate about whether Congress should be “allowed” to vote or not.

Congress needs to get out of the way and let the negotiators finish the job. Diplomacy is the only way to achieve a stable, long-term solution to the Iran nuclear crisis. A good deal is within reach—one that would keep Iran’s nuclear program peaceful by setting firm limits and locking in intrusive inspections that would deter Tehran from violating the agreement.

So keep talking to Iran. Diplomacy is much better than the “wildly unattractive” alternatives.

Tom Z. Collina is the Policy Director at Ploughshares Fund in Washington, DC.

Image: Flickr/US Mission Geneva