NOW THAT HE'S BACK IN the elections business, Karl Rove has a huge task on his hands: assuring strong Republican voter turnout. At the moment, Republicans are in a funk. And their dejected mood may presage a low turnout in the midterm election on November 7. Should a large number of Republican voters sit this one out, Republicans could lose control of one or both houses of Congress. It's when Republicans are either inspired or angry that they show up in large numbers and win elections. So Rove, along with Republican national chairman Ken Mehlman, has the job of shaping issues that will make Republicans angry or inspired, or both.

There's one big problem--two, actually. First, Rove's magic won't affect the biggest issues dogging the Bush presidency and causing Republicans to be disheartened: Iraq and rising gas prices. But the second problem--President Bush's sagging job approval among Republicans--is one that Rove can address by emphasizing policies that appeal to Republicans and by creating strong fears of a Democratic takeover.

Let's be clear about turnout. It matters enormously. The sweeping Republican defeat following Watergate in 1974 was only indirectly related to the scandal. The Democratic landslide was directly attributable to the diminished Republican turnout that resulted from Watergate-induced dejection among Republicans.

More recently, the turnout factor has been the single greatest influence on midterm elections. In 1990, 27.4 million Americans voted for Republican House candidates, and the party lost 8 seats. In 1994, however, the Republican turnout jumped to 36.3 million, and the party captured

In presidential election years, jacking up turnout is relatively doable, as the Bush campaign showed in 2004. Presidential elections unleash "incredible energy," a senior Bush adviser says, and that generates volunteers, donors, a campaign infrastructure, and a flood of voters to the polls. "By definition there's less energy," says the adviser, in nonpresidential years--and less infrastructure for a national campaign. The "key" in these years, the adviser continues, is to make "your base as inspired as possible."

With the 2006 midterm election six months away, the Republican base is uninspired. In the Fox News poll in mid-April, only 66 percent of Republicans said they looked favorably on the Bush presidency. This is a disastrous number for Republicans. Of course, it wasn't as bad as the overall Bush rating of 33 percent, which included Democrats and independents.

Low job approval can have a double whammy effect. By itself, a 66 percent rating means that turnout by Republicans is likely to be low. In 2002 and 2004, when Republicans won House seats, Bush's approval among Republicans was 20 or more points higher.

The second effect is to cause further Republican disenchantment. Low poll numbers like 33 percent approval are bound to prompt some Republicans to feel they must separate themselves from Bush and join in criticizing him and Republicans in Congress. This, in turn, leads to lower turnout.