There’s a hidden history to the nasty midterm election campaign that will, mercifully, end on Nov. 4. What’s not being widely talked about is as important as what’s in the news.

Underappreciated fact No. 1: The number of Democratic seats that are not in play this year.

In planning their effort to take control of the Senate, Republicans shrewdly launched challenges to Democrats in states that would not automatically be on a GOP target list. “Broadening the map” is wise when you’re in a strong position.

Two of the states on that extended list, Colorado and Iowa, have paid off for Republicans. It’s still far from certain that they will defeat Sen. Mark Udall in Colorado or Rep. Bruce Braley in Iowa, who is trying to hold retiring senator Tom Harkin’s seat. Republicans have a clear shot at both, and this has strengthened their chances of taking the majority.

Just as striking is how many Democrats seem to have nailed down races the Republicans had once hoped to make competitive. This has narrowed the GOP’s path to a majority. Among them: Sen. Al Franken of Minnesota, Sen. Jeff Merkley of Oregon and Rep. Gary Peters of Michigan, who is likely to retain Sen. Carl Levin’s seat. Sen. Mark Warner of Virginia is also polling well, though he was always favored against former Republican National Committee chairman Ed Gillespie. Sen. Jeanne Shaheen of New Hampshire is in a tougher race with former Massachusetts senator Scott Brown, but she has led most of the way.

Democrats have benefited in these states from their opponents’ shortcomings. But what has been lost in the national news is underappreciated fact No. 2: How important economic issues have been in shoring up the party’s incumbents and in giving life to Democratic challengers in Georgia, Kentucky and (a much longer shot) South Dakota.

It’s commonly said that Republicans are nationalizing the elections against President Obama while Democrats are making them about “local” issues. That is true of North Carolina, where Democratic Sen. Kay Hagan has, so far successfully, targeted the unpopular Republican state government. But elsewhere, endangered Democrats are campaigning on a different set of national concerns related to economic worries. These include equal pay for women, relief for student loan recipients and a minimum-wage increase. Several Democrats, including Shaheen and Michelle Nunn in Georgia, have made an issue of opposing the outsourcing of U.S. jobs overseas.

This leads to underappreciated fact No. 3: Given Obama’s low approval ratings, Republicans could have been running away with this thing. They’re not, because they look more extreme and out of touch than they did four years ago.

A Pew Research Center survey conducted Oct. 15 to 20 found that Democrats had a 21-point advantage among registered voters as the party “more concerned about needs of people like me,” up from a lead of only 11 points in October 2010. Voters picked Republicans over Democrats as the party “more influenced by special interests” by 46 percent to 32 percent, a 14-point Republican deficit, up from an 8-point deficit four years ago. And on a new measure, voters declared the Republican Party “more extreme in its positions” by 52 percent to 36 percent.

Underappreciated fact No. 4: While opposition to Obama will motivate Republican turnout, particularly in contested red states, close races will hang on voters who are not casting ballots either for or against the president. The Pew survey found that 32 percent of voters saw their congressional ballot as a vote against Obama, and only 20 percent as a vote for him. That’s the GOP advantage.

But 45 percent said Obama would not be a factor in their decision. And within this group, 60 percent are Democrats or independents who lean that way and only 28 percent are Republicans or Republican-leaners. This is why Sen. Elizabeth Warren (D-Mass.) and Bill and Hillary Clinton have been in such demand on the campaign trail. Their messages, particularly Warren’s, have been about economics, which brings us back to fact No. 2. Warren has been especially effective in tagging the GOP as in league with the wealthy and the special interests, a lesson that forcefulness is more likely to grab voters’ attention than running scared is.

Many Democrats quietly concede that the Senate playing field still tilts the Republicans’ way. If Democrats upset expectations, these underappreciated factors will be the reason. If the Republicans prevail, the fact that the election has been so closely fought points to problems that even a victorious GOP will have to confront.

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