WASHINGTON — Republicans and Democrats are struggling for control of the Senate in this November’s midterm elections. But there is no real fight for control of the House of Representatives.

The Republicans are all but assured of retaining control of the House, despite last fall’s unpopular government shutdown and the party’s dismal ratings.

“The Republican hold on the House is the graveyard of the hopes of Democratic policy change,” says Neera Tanden, president of the liberal-leaning Center for American Progress. It has stifled not just President Obama’s agenda, but also the aspirations of his coalition of young, secular and nonwhite voters, who have represented a majority in presidential elections.

How is it possible that the Democrats, who have won the popular vote in five of the last six presidential elections, are at such a disadvantage in the House, theoretically the most representative body of government? It is the biggest paradox in American electoral politics.