On Tuesday, Congress accomplished something relatively rare: It passed a piece of legislation and sent it to the president for his signature.

On a broad bipartisan vote of 78 to 20, the Senate voted Tuesday to extend the life of the U.S. Export-Import Bank and expand its authority to make loans to U.S. exporters.

In the “Schoolhouse Rock” version of how Capitol Hill works, this is what Congress does all the time — passes bills. But in the current reality defined by protracted partisan warfare, the voting has been mostly a show in which one party or the other forced a vote merely to demonstrate the other’s opposition.

With the exception of post office namings, the last measure approved by both Republicans in the House and Democrats in the Senate was signed into law by President Obama on April 5. That legislation was designed to make it easier for growing businesses to raise capital.

Amid the gridlock, Tuesday’s bill was the rarest of breeds: a lasting compromise on an issue of substance. It renewed the charter of what is commonly referred to as the Ex-Im Bank for three years and will, over that time, raise the limit on the total financing the bank can guarantee borrowers, from $100 billion to $140 billion.

The nearly 80-year-old bank makes loan guarantees to foreign buyers who seek to do business with U.S. exporters.

The House agreed to the same measure by a similarly broad 330 to 93 vote last week.

The measure was approved over the objections of some tea party conservatives who argued that the bank distorts the global marketplace and that propping up U.S. exporters is an improper role for government. But it had the backing of business and labor groups.

Depending on who’s talking, the fact that it was the Ex-Im Bank that provided the opportunity for election-year cooperation was a hopeful sign that occasional bipartisanship is still possible in Washington or further evidence of the huge influence that corporate interests continue to hold over both parties.

The bank has been reauthorized with little notice dozens of times before, and the U.S. Chamber of Commerce, the National Association of Manufacturers and others had been pushing Congress to do so again. The bank’s temporary authority was set to expire at the end of the month.

The groups argued that export subsidies help level the global playing field for U.S. companies competing with foreign businesses that are given significantly more support by other governments.

Proponents said the bank’s loans support 200,000 jobs at big and small companies nationwide.

“There are no Democratic or Republican exports. There are exports that create jobs. Good, middle-class jobs,” said Fred P. Hochberg, president and chairman of the Ex-Im Bank.

Both chambers have held plenty of votes in recent weeks but largely on issues embraced by only one side.

The House approved a bill that would prevent student loan rates from rising — but paid for it by eliminating funding for preventive health care. The measure can’t pass the Senate.

Senate Democrats proposed legislation that would fund the same student loan rate cut by closing a tax loophole that some small businesses use. Republicans blocked it.

Veto threats from the White House have become routine — although largely empty, and issued in response to bills under consideration in the House that will not ever win Senate approval.

The dynamic has led to frustration on both sides, and not a small amount of gallows humor.

“I just think we’re moving way too quickly around here,” Sen. John McCain (R-Ariz.) said before the vote, suggesting the lag time between legislative victories should be more like three or four months. “It’s just all been a blur.”

Detractors of the Ex-Im Bank bill, including McCain, argued that although no taxpayer money is used in bank deals, the bank is designed to offer guarantees in cases that private lenders deem too risky, and detractors worry that taxpayers could be on the hook if those deals go south.

Among its opponents was the Club for Growth, which put wayward Republicans on notice last week by spending nearly $2 million to help Indiana state Treasurer Richard Mourdock defeat Sen. Richard G. Lugar in the state’s Republican Senate primary. The Club argued that the six-term senator has not been sufficiently committed to conservative fiscal policy.

“What this shows is that members of Congress in both parties are opposed to subsidies — except when it affects a favored industry,” Club for Growth spokesman Barney Keller said. “Democrats won’t eliminate welfare for supposed green jobs. And the Republicans won’t eliminate it for massive multinational companies that don’t need it.”

Passage was made possible by a deal crafted in the House by Majority Leader Eric Cantor (R-Va.) and Minority Whip Steny H. Hoyer (D-Md.) in which the bank would be subject to new reporting requirements.

Republicans who backed the measure said American businesses would be hurt if the country halted its export support while other nations continued to assist their own companies.

“I live in the real world and the real world is that these financing mechanisms have to be available to American manufacturers to have a share of the overseas market,” said Sen. Lindsey O. Graham (R-S.C.).

The measure was approved after the Senate rejected five GOP-sponsored amendments that would have weakened or shuttered the bank.

Graham said the robust debate on amendments is a sign that the Senate is “back in business.”

But he said he hoped that fledgling governments worldwide, such as Afghanistan’s, don’t rely on C-SPAN to get a sense of how American governance works.

“Who are we to lecture anyone about democracy given the way we’re behaving?” he said.