Illegal immigration never panned out as the major wedge issue Republicans hoped it would be when they lost control of Congress in 2006. But with more seats on the line in 2007, they have been turning to the issue repeatedly as a special-election trump card and hoping it will work under the right set of circumstances.

Tuesday’s special House elections in Ohio and Virginia will be the next test of the issue’s potency as Republicans evaluate its effectiveness going forward and Democrats continue to search for a way to finesse it.

The Democrats, meanwhile, have been trying to carve out a middle ground and even leaned to the right in some cases, hoping to blunt the impact of the wedge and add to their list of 2006 red-district upsets.

Ohio state Rep. Bob Latta (R) and Virginia state Del. Rob Wittman (R) both enter the voting as the favorites. But in Latta’s case in particular, a close result or upset does not appear to be out of the question.

Latta and the National Republican Congressional Committee have attacked Democrat Robin Weirauch for supporting a bill that some say would provide health care to illegal immigrants, and Latta launched a television ad last week focusing exclusively on the issue.

In Virginia, Republicans are heavily invested in linking Democrat Philip Forgit to national party leaders like Sen. Hillary Rodham Clinton (D-N.Y.), and saying he would be easy on illegal immigrants.

The approaches resemble the strategy used by retired Air Force Lt. Col. Jim Ogonowski (R), who in October ran a closer-than-expected race in a Democratic-leaning district in Massachusetts.

Ogonowski ran a radio ad in the closing week of the campaign accusing now-Rep. Niki Tsongas (D) of supporting driver’s licenses for illegal immigrants, and he focused heavily on that issue toward the end.

Both Weirauch and Forgit have employed tough enforcement messages and shied away from aspects such as citizenship, which has been a cornerstone of the Democratic platform on the issue but might hurt them in GOP-leaning areas.

Weirauch disputes that the bill she advocated, authored by Rep. John Conyers Jr. (D-Mich.), would cover illegal immigrants, and she has promised to go hard after those who employ illegal immigrants.

Forgit says issues like citizenship should be addressed after the border is enforced. And in a debate over the weekend, he fought back by accusing the Republicans in Washington of failing to confront the issue during their time in power.

“For six years, [Republicans] had total power, under President Bush, and did nothing about the borders, and yet the Republicans have somehow turned this into a state election issue, and now it’s a federal issue,” Forgit said. “The fact is: they defaulted on their responsibility to defend the border.”

The stances echo a posture taken by some vulnerable and freshman Democrats in the House who have coalesced behind an enforcement-first immigration bill authored by freshman Rep. Heath Shuler (D-N.C.).

The continued kneading of the issue on the GOP side comes after a series of border-hawk Republicans went down to defeat in the 2006 election, including a pair in battleground districts in Arizona.

Rep. Jeff Flake (R-Ariz.), who won reelection, said at the time that GOP leaders foolishly expected a hard-line illegal immigration stance to make up for their woes on other issues.

Independent pollster John Zogby said the issue remains powerful for Republicans, especially as a sound bite. But he cautioned that they could hurt themselves by alienating the growing Hispanic vote.

In a poll released last week, he found that immigration is gaining on the war in Iraq as an issue at the top of voters’ lists of priorities, a development that appears to favor Republicans.

“If they’re not beset by corruption, not hurt by the war, if they’ve got a fresh face promising change just as much as the Democrats, this issue could be that ultimate wedge issue for them,” Zogby said at a breakfast hosted by the Christian Science Monitor.

Illegal immigration has increasingly become as a hot-button issue in the presidential race in recent weeks as well. It is still pushed primarily by Republicans, while some Democrats have struggled with it.

Clinton saw her presidential campaign hit a rough patch after she struggled to take a position on driver’s licenses for illegal immigrants in late October.

Then, at a National Public Radio debate in Iowa last week that focused heavily on the issue, she suggested economic problems were at the root of the issue and called it a “contentious, demagogic debate.”

Sen. Chris Dodd (D-Conn.) said at the debate that the GOP is putting the issue on the table for lack of anything better to talk about.

“They’re going to use this issue as a wedge issue here to inflame the passions, the fears and hatreds of too many Americans,” Dodd said. “We have seen it in the past in our country. It’s dangerous politics, and we need to describe it for what it is.”