Americans who are 18 and older on Tuesday will elect governors, state legislators and members of Congress in nationwide voting that comes in the middle of President Obama's second four-year term. That's why this week's decisions are called midterm elections. Even though the country's top political job isn't at stake, the House and Senate outcomes affect relations between the Democratic president and Congress.

If Republicans gain at least Senate seats, they'll have a majority in that 100-member branch on Capitol Hill. They have a decent chance of doing so, polls show. In the 435-member U.S. House, Republicans are considered almost sure to keep the control they've had since 2010. The question is how many seats they may gain. If they add a dozen House members, Republicans will have an advantage not seen since 1948.

Still, a notably sour electorate and a sizable number of undecided voters create suspense. "Maybe venting will make the atmosphere a little less gloomy," comments a popular national blogger, Andrew Sullivan. "That's one function of elections, after all. But after that, the harder but more vital task of deciding how to address that gloom with policy and direction is up for grabs."

Democrat says: "It's a grim environment. It's very tough terrain." – Rep. Steve Israel of New York, head of the Democratic Congressional Campaign Committee

Republican says: "It's not as though people have all a sudden fallen in love with Republicans. It's just a loss of confidence in the administration. . . . People are on edge. And that’s not good if you’re the party in power." – Sen. Senator John Cornyn of Texas

Newspaper says: "This stuff really matters. . . . Democracy is America's civic religion. It’s good for your soul . . . to participate with others in the secular rite of voting, an act that legitimizes for each individual our continuing national experiment in self-government." -- Valley News editorial in White River Junction, Vt.