Ohio Republicans will attempt to pass a revised Congressional map Thursday afternoon that aims to enhance minority voting power in four cities.

The new map marks the GOP’s final compromise offer to black Democrats, as well as Republicans’ last attempt to avert a major legal and political battle over the new map.

Republicans have been working with black Democrats in the state Legislature for weeks to forge an agreement over a new map. The GOP needs seven votes from state House Democrats to pass a new map as emergency legislation, which means Democrats cannot put the map in front of voters as a referendum on the 2012 ballot.

“This map addresses some of the concerns of the black caucus in the Legislature and some other concerns among some of the other Democratic Members,” said former Ohio Republican Party Chairman Bob Bennett, the GOP’s appointed negotiator with the state’s black legislative caucus.

But two well-placed GOP sources cautioned Wednesday night that they weren’t sure if they had the necessary votes.

“We don’t know whether we have the votes or not,” one of the sources said. “We’re going to do an up-or-down vote, we’re going let the chips fall.”

The new proposed map does not make sweeping changes to the map already signed into law, but it does consolidate black voters in the major cities including Dayton, Columbus, Cincinnati and Toledo.

Nonetheless, the effects of those minor changes in Dayton could change at least one Member-vs.-Member race next year.

GOP Reps. Michael Turner (R) and Steve Austria (R) were moved into the same district under the first map. That won’t change under the new map, but one source mentioned the new map could make freshman Rep. Steve Stivers (R) a more enticing opponent for Austria.

If Republicans can’t summon the votes to pass the map as emergency legislation, Democrats will continue collecting the necessary 231,000 signatures to put the map on the 2012 ballot as a referendum. In the meantime, courts could step in and decide an interim map for 2010 — a worst-case scenario for Republicans.

A copy of the new proposed map will be available Thursday morning, Mike Dittoe, a spokesman for Ohio House Speaker William Batchelder, confirmed.

The GOP’s bill also schedules all primaries on the same date in March. Under previous legislation, the Congressional and presidential primaries were moved to June.