House Republican leaders have had a rough time lately getting bills through the legislative process. Most recently, they watched as their proposed three-week funding bill for the Department of Homeland Security (DHS) was unexpectedly defeated, forcing them to enact a one-week funding bill just hours before the agency would have run out of money.

As Jeff Jenkins rightly notes, the defeat of the measure was unusual: The House majority party almost never brings bills to the floor if it doesn’t have the votes to pass them. When such measures do lose, these “disappointment” votes usually make the majority look bad.

After votes like these, the finger of blame usually points toward either the leaders of the majority party or defectors within it. But another essential player is responsible for majority party losses that people sometimes forget: the minority party.

In the case of the DHS funding bill, only a dozen House Democrats voted for the measure, nowhere near enough to counter the 52 Republicans who voted no.

This was no accident. In fact, minority party leaders actively whipped their members to reject the measure, and most of the Democrats who supported it “held their votes close to the vest,” forcing GOP leaders to search in vain for help from within their own ranks. (You can see it happening as the vote unfolded.)

Although “disappointment” votes may be rare, the House minority party’s ability to make life difficult for the majority — or even influence policy — is greater than many realize.

For instance, when it comes to floor votes, the minority party can prevail over the will of the majority party in several ways: through “disappointments” (when a majority party measure is defeated), via “rolls” (when proposals pass over the opposition of the majority party), or on amendments to bills as well as bills themselves. Taken together, these outcomes occur more frequently than just “disappointments,” sometimes 15 percent of recorded votes or greater.

There are additional tactics the minority can use besides voting to challenge the majority or even shape policy. News conferences can bring attention to issues the majority would prefer to ignore; amendments can be offered to alter bills; and chamber rules can be exploited to delay proceedings or force votes on embarrassing issues.

The minority party’s influence depends on several factors. Two of the most important are its size and unity relative to the majority. Small, divided minority parties are less powerful than large, unified ones. If House Minority Leader Nancy Pelosi’s Democrats can stay as unified as they were on Friday, they are likely to have a lot of leverage in this Congress.

Other variables, such as party morale and the skill of party leaders, also affect how influential and active the minority party is. In the 103rd Congress (1993-94), House Republicans had a smaller majority than Democrats do now, as well as an opposing president, Bill Clinton, to contend with. But their unity and tactically inventive and assertive members — Newt Gingrich, first and foremost — enabled them to frustrate majority Democrats on multiple occasions.

The DHS funding fight illustrates one other important determinant of minority party strategy: presidential politics. When the minority party has a same-party president in the White House (as is currently the case), it is especially sensitive to efforts by the majority to undermine the president’s agenda or authority. At the same time, however, the president often needs the help of Congress to govern, so the minority party habitually feels pressure to cooperate with its partisan nemesis.

These contradictory impulses may help explain what happened Friday. When Republicans declared that they would use DHS appropriations to block President Obama’s executive action on immigration, it became a call to arms to congressional Democrats.

Yet as soon as the GOP’s three-week spending measure died, Democrats quickly agreed to support the bill that funded DHS for a week. Minority party leaders reportedly did so as part of a deal with Republicans, but they may have also feared that any additional brinkmanship would burden Obama with a distracting and potentially dangerous shutdown of an important Cabinet agency.

There is no doubt that the internal divisions of the House GOP are substantial and consequential, and they are likely to cause party leaders more headaches in the months ahead. But if governing continues to be a challenge for the majority Republicans, we shouldn’t forget to credit — or, depending on your point of view, blame — the minority Democrats, too.

Matthew Green is an associate professor of politics at the Catholic University of America. His most recent book, Underdog Politics: The Minority Party in the U.S. House of Representatives, was published in January by Yale University Press.