WASHINGTON — The pro-NAFTA forces in Washington are promising to try saving the agreement with a fight that could culminate in using legislative action to protect it from President Donald Trump.The U.S. Chamber of Commerce will hold weekly events to rally support for the deal, representatives said Tuesday during a gathering at its headquarters across the street from the White House.Two of the speakers were prominent Republican senators who urged everyone who supports the agreement to raise their voices in defending the deal, thereby helping to tilt the scales amid an internal debate within the White House about whether to cancel the deal as a hardball negotiating ploy.One senator from Kansas dismissed that as a “Humpty Dumpty” strategy that would break NAFTA first, and attempt to fix it later. Pat Roberts called it a risky approach and said he has personally confronted the president three times over the issue.The latest came at a caucus meeting last week where Trump told Republican lawmakers not to get excited over his negotiating ploy, and Roberts replied to the president: “I am excited.”Speaking after his colleague Sen. Ted Cruz, Roberts said it’s imperative that people who believe in trade speak out now to counter the anti-trade impulses in Trump’s Washington.“Saddle up. Everybody saddle up. We have to ride. Ride with me,” Roberts said in a speech.“We are fighting a pervasive view that our economy has not benefited from NAFTA. That is simply not right. We are coming to a crossroads… These issues affect real jobs, real lives and real people.”Both senators described how their states have benefited from NAFTA; Kansas, for instance, is a significant exporter of agricultural products like wheat. A number of farming groups have warned that the mere threat to cancel NAFTA could send foreign customers scrambling to find new non-U.S. suppliers.Roberts briefly addressed the emerging debate over whether his fellow lawmakers might step in to take legislative measures to counter a presidential pullout. The U.S. Constitution gives Congress power over international trade, and some analysts like former U.S. trade czar Robert Zoellick have urged it to flex those muscles by taking legislative steps to wrest some control away from the White House.Asked whether his colleagues are discussing such steps, Roberts said: “That might be an option. Right now I think it would be a little early to be doing that… I think we can make our case before the administration.”Cruz said his GOP colleagues are almost universally pro-trade.“The Republican conference and Senate is virtually united,” he told the business crowd.“I want to encourage everyone in this room: Let your voice be heard. Because the administration is being pulled in two different directions.”The U.S. Chamber of Commerce has sounded the alarm over what it sees as potentially fatal moves to undermine the agreement by the Trump administration amid negotiations to upgrade the deal.Those moves include demands by the Trump administration for a five-year termination clause allowing easy cancellation of the agreement; tougher Buy American rules; auto-parts requirements the industry calls impossible to meet; and a gutting of the dispute mechanisms that enforce NAFTA.“For many in the business and agriculture community, the outlook has shifted over the past month. There’s growing concern about the direction of the negotiations,” said John Murphy, the chamber’s vice-president.“A number of the proposals that the United States has put on the table have little or no support from the U.S. business and agriculture community. It isn’t clear who they’re intended to benefit…. (They) will only add costs for business, add to uncertainty, depress investment…“But I think many in Congress are catching up to those concerns. They’re increasingly hearing from their constituents. Threats to withdraw from the agreement are catching attention.”More than 80 agriculture groups wrote to the administration last week urging Trump not to use NAFTA’s pullout clause as a negotiating tool. That clause, Article 2205, allows a country to provide six months’ notice of its intention to withdraw.“Withdrawal is looked upon as a potential catastrophe,” Murphy said. “So I do think members of Congress are rapidly coming to grips with those concerns, as they’re hearing them from their constituents.”The Republican senators at the event did not discuss the far bigger story currently engulfing Trump’s Washington: the Russia probe, which has just produced its first three arrests, including ex-campaign manager Paul Manafort, as well as its first guilty plea and its first target-turned-informant.Former campaign foreign-policy adviser George Papadopoulos has admitted to communicating with intermediaries for the Russian government about the possibility of collecting dirt on Hillary Clinton, via illicitly obtained emails.Authorities say he is now co-operating. The Trump administration says he was merely a low-level adviser whose acts do not reflect on the campaign.