President Trump speaks with Russian President Vladimir Putin on a Jan. 28 phone call in the Oval Office. (Pool photo by Pete Marovich via Bloomberg News)

This week, in a 98-to-2 vote, the Senate approved a bill that tightens sanctions on Russia and restricts the president’s ability to lift those sanctions. That bipartisan support came even though the Trump administration is vigorously opposed to the measure, arguing that the bill, which now goes to the House of Representatives, could hurt efforts to improve U.S.-Russia relations.

It’s easy to assume this disagreement comes because of President Trump’s unusually pro-Russian orientation and the current scandal about Russian interference in the 2016 election. But that’s not so. During the past several decades, the president and Congress have often fought about sanctions on countries ranging from China to Iran. In fact, the question of sanctions seems to shift the usual D.C. divisions, bringing together Republicans and Democrats in Congress in opposition of the president.

The pattern of inter-branch conflict over sanctions

Congressional proposals to issue sanctions regularly attract broad bipartisan support among lawmakers and opposition from the president, according to my research. Between 1983 and 2014, CQ Magazine, an outlet that covers congressional activity in depth, reported on 104 legislative proposals to impose new sanctions on another country. These included proposals to sanction dozens of countries based on economic, national security, human rights or drug-related concerns.

Of those 104 legislative proposals, 67 were approved by a majority of Democrats and a majority of Republicans every time lawmakers voted on them. On the other hand, the president opposed at least 76 of the 104 proposals. These patterns held even as polarization increased under presidents George W. Bush and Barack Obama.

Why would the branches disagree so often about sanctions?

Because lawmakers and presidents face different incentives for their foreign policy positions.

Members of Congress are often rewarded or praised by engaged constituents or advocacy groups for taking strong positions, even if those positions might complicate elements of U.S. foreign policy. This liberates lawmakers to place principle over pragmatism, pushing for far-reaching sanctions on governments engaged in objectionable behavior.

By contrast, the public holds the president responsible for the economy’s health and for foreign policy successes and failures. As a result, presidents worry more than lawmakers about how sanctions might prompt economic retaliation or strain diplomatic ties. Even if presidents do support the use of sanctions, they often resist the penalties proposed by lawmakers, arguing that they are too sweeping and restrict diplomatic flexibility.

In fact, Congress and the president have clashed over Russia sanctions before

Trump isn’t the first president to clash with Congress over Russia sanctions. During the 1990s, Bill Clinton worried that bills penalizing Russia for military links to Iran would damage relations with the Russian government. He even vetoed one such bill, forcing Congress to revise the legislation so that he had more discretion over how to implement it.

During Obama’s first term as president, the administration resisted a congressional proposal to impose a travel ban on, and freeze the assets of, Russian officials responsible for gross violations of human rights. (Full disclosure: I worked on this legislation as an aide to Rep. Jim McGovern (D-Mass.), who introduced the bill in the House.)

At the time, Obama still hoped for a constructive relationship with the Russian government. And so the administration argued that the measure would reduce Russian cooperation on important U.S. foreign policy priorities. Nevertheless, Congress approved it with strong bipartisan support — and coupled it with a trade bill Obama favored, making it hard to reject. Obama opted to sign, rather than veto, the legislative package.

After Russia invaded the Crimean Peninsula in 2014, lawmakers proposed a broader set of sanctions on Russia. This time, Congress and Obama were not as sharply at odds; Obama had already used his executive authority to join European allies in imposing penalties on Russia.

But Congress backed more far-reaching sanctions than Obama did. As the sanctions legislation advanced in Congress, Obama cautioned that it would be counterproductive for the United States to get out in front of its European allies, weakening the transatlantic coalition’s united front. But Congress passed the legislation with overwhelming bipartisan backing, making a veto unpalatable. Obama signed the measure into law.

What does congressional bipartisanship on sanctions really mean?

Most people usually think of bipartisanship as an occasion when Republican and Democratic lawmakers line up to support the president, as when Congress rallied around George W. Bush following the 9/11 terrorist attacks. That’s the kind of unity implied by the adage that “politics stops at the water’s edge.”

But sometimes bipartisanship means lawmakers work together across party lines against the president. And it doesn’t just happen over sanctions. For instance, leading lawmakers in both parties have sharply criticized Trump’s proposal to slash spending on diplomacy and foreign aid by about 30 percent.

So what’s the effect of sanctions laws?

Apart from the merits of any given presidential policy, congressional assertiveness on sanctions can have a cost. Critics argue that sanctions laws make it harder for the president to conduct an effective foreign policy, particularly because Congress is often unwilling to repeal sanctions even when the president achieves a diplomatic breakthrough with the targeted country.

But sanctions laws can also carry important benefits. Scholars have shown that leaders, paradoxically enough, often enjoy stronger bargaining positions internationally when they face domestic constraints at home. The logic is straightforward: If leaders can make a strong case to their foreign counterparts that their hands are tied, those counterparts may offer concessions as a way to strike a deal or avoid unwanted punishment. When presidents want to hold foreign governments to account, legislation can give their sanction threats more credibility and bolster their leverage.

What’s more, when presidents don’t want to pressure foreign governments, a sanctions law can force them to do so. Today’s Congress may view sanctions as a way to counteract Trump’s willingness to overlook, or even praise, foreign leaders whose actions are illiberal or even threaten U.S. interests. But it would not be the first time that Democratic and Republican lawmakers have banded together in an effort to stiffen presidential policy toward another country.

Jordan Tama is associate professor at American University’s School of International Service and co-editor of the forthcoming sixth edition of the book “Rivals for Power: Presidential-Congressional Relations.” He served in 2011-12 as an American Political Science Association Congressional Fellow.