The Republicans are torn by the struggle among the establishment, tea partiers and the forces of Trump. But the Democrats also have an identity war.

Don’t forget: the Democrats have a long history of including widely differing opinions. Also, no matter what the GOP says, not all Democrats are liberals.

In fact, there’s a good deal of overlap between moderate Democrats and establishment Republicans. That similarity is what led to the conservative takeover of the GOP and liberal complaints about candidate Hillary Clinton. It is also what has produced congressional action.

A relatively clear liberal-conservative split exists on so-called social issues: abortion, same-sex marriage and guns. Those issues divide Democrats and Republicans, as do differences over the Affordable Care Act.

Clinton and Bernie Sanders are usually seen on the liberal and Democratic side of these issues. But not all Democrats agree, while a few Republicans may quietly side with them.

The real split among Democrats comes on economic issues and the role of government. The current campaign has revealed a strong effort to turn the party away from its drift toward support for smaller government, more power for the private sector, and continued low income taxes.

Sanders has adopted a forthright liberal approach. He sees an essential role for government and the need to raise taxes. He blames most of the country’s problems on the superrich and major financial institutions.

His support for bigger government, a tax increase and breaking up the biggest financial institutions would likely lead to his being labeled a socialist, but he has diffused the charge by saying he is one. Besides, the government role he advocates is considerably less than the quasi-socialist regimes of Scandinavia.

His candidacy has become an effort to gain increased power, maybe even control, over the Democratic Party. The GOP bred the “tea party” movement. With Sanders, the Democrats may have spawned the “new revolution” movement, to borrow his term.

Sanders needs a revolution, because, even if he were president, he would depend on Congress to approve his policies. His allies would have to be elected to Congress, just as tea partiers have been.

The traditional GOP has gradually adopted the tea party’s positions. Similarly, Clinton has given some ground to Sanders in the course of the campaign. It is generally thought he has pushed her to the left.

Yet Clinton, like Democratic presidents Carter, Clinton and Obama, clings to her allegiance to what she might consider the moderate center of American politics. That view has meant a major role for big business and big finance in recent Democratic administrations.

The symbol of Clinton’s sympathies for these parts of what may be a broad Democratic coalition is her refusal to release the texts of highly paid speeches she made to Wall Streeters. The voter is left to wonder if she buttered up her audience in hopes of later support by them.

The conventional wisdom is that Sanders is foolish in believing that America is ready for revolutionary change that would increase the size of government, raise taxes and weaken major economic powers.

Sanders appears to believe that Republican-driven cuts in government programs have gone so deeply into what people regard as essential services, voters would be willing to support higher taxes or even more debt.

Like Donald Trump on the other side of the street, Sanders believes that conditions have grown bad enough that voters, both traditional and new, are ready to take drastic action. Obviously, he thinks he offers a fair and workable alternative for the Democrats.

After all, by following their more moderate approach, the Democrats have not fared well. President Obama gets little credit for the economic recovery, but voters rate him unfavorably because of his health care program and his position on guns. The Democrats have lost control of both houses of Congress and could lose the presidency.

Even if his new revolution cannot prevail this year, Sanders might reason that a strong showing would exert force on the Democrats just as the tea party did on the Republicans. It is reasonable to see his campaign, not as a quixotic attempt to win, but the launching of an historical political change.

The country abandoned its conservative political tradition in electing Democrat Franklin D. Roosevelt in 1932, believing that his proposals, involving a greatly increased federal government, were needed to end the Depression.

The battle for the Democratic Party now turns on whether there is sufficient concern, especially among younger voters, that political and economic conditions are so bad that a new political revolution is warranted.