When the president calls a treaty “a national security imperative,” you would think rallying Republican support would not be difficult.

And in fact, President Obama has gotten strong Republican backing for a new nuclear arms agreement with Russia. At a White House meeting demonstrating bipartisan support for the treaty last week, he was joined by former secretaries of state Henry Kissinger and James A. Baker, and former National Security Adviser Brent Scowcroft.

One key Republican is not on board, however. Republican Sen. Jon Kyl of Arizona, whose influence on this issue is critical in the Senate, announced last week that he would not support ratification of the New Start treaty this year.

Nuclear arms control is vital to our national security. This principle was emphasized in an earlier letter of support for the new treaty signed by 30 foreign policy experts from both political parties. When the arms control treaty expired last year, it put an abrupt end to limits on nuclear weapons and mutual inspections.

The new version sets lower a cap on Russian and American nuclear stockpiles, and it reportedly provides for more rigorous inspections of each side’s arsenal. Reproaching the Republican senators who oppose the treaty, Obama echoed former President Ronald Reagan, who expressed his approach to arms control with a much-quoted aphorism: “Trust but verify.”

The goal of limiting nuclear proliferation should begin with a U.S. commitment. The proposed agreement between the U.S. and Russia provides a demonstration of good faith that would support efforts to restrain North Korea, Iraq and other nations.

The New Start treaty was signed by Obama and Russian President Dmitry Medvedev months ago, but requires a two-thirds vote in the Senate for approval. That goal became more difficult last week when Kyl opposed ratification and asserted priority for a separate goal of many conservatives ”“ modernization of U.S. nuclear weapons.

Some Republicans also argue that the treaty overly restrains U.S. weapons deployment, while hardly scaling back Russian stockpiles at all. Perhaps the bottom line for many is the opportunity to put the president at a political disadvantage.

Can the broad support for this treaty by foreign policy heavyweights simply be dismissed for political purposes by GOP senators? If so, the tide of partisanship has risen alarmingly high.

— Questions? Comments? Contact Managing Editor Nick Cowenhoven at nickc@journaltribune.com.