The 2012 election between Obama and Republican nominee Mitt Romney was billed as a great debate between competing views of government and a moment when voters could signal a clear direction for the country.

Instead, the election continued the status quo in Washington, with neither a slackening in partisanship nor a narrowing in the philosophical gap between the parties. If anything, it reinforced rather than eased the divisions that existed. Gary Jacobson, a political scientist at the University of California at San Diego, described 2012 as “the most partisan, nationalized . . . election in at least six decades.”

Over the past two decades, the percentage of self-identified Republicans and Democrats who support their party’s presidential nominee has ticked higher and higher. In the past three elections, according to American National Election Studies data cited by Jacobson, 89 or 90 percent of Republicans and Democrats backed their party’s nominees. Three decades ago, those percentages were considerably lower.

What made 2012 more significant was the degree to which voting in House and Senate elections followed a similar pattern. In each case, nine in 10 partisans backed their party’s candidates for either House or Senate races.

The 2012 election represented a high point for trends that have increased polarization. In the 1980s, another period of divided government, a quarter of the electorate voted for president one way and the House or Senate another way. In 2012, only about 11 percent of voters in the ANES studies cited by Jacobson said they split their tickets.

What’s important about this is that there is now almost no intersection between the coalition that elected the president and the one that elected the majority in the House. Members of Congress have far less incentive to compromise with a president of another party if they know they are not dependent in any significant way on that president’s supporters.

“If you look at the people who elected Obama and the people who elected the Republicans in the House, there’s very little overlap,” Jacobson said. “They owe their victories to very different constituencies, to folks who are pretty divided on every political issue.”