By Andy Sullivan and Jacqueline Thomsen WASHINGTON (Reuters) -In the months leading up to the U.S. midterm elections, lawyers for Democrats and Republicans are already squaring off in a wave of lawsuits challenging state rules on how to vote and the counting of ballots. Here is a summary of significant cases filed ahead of the Nov. 8 election and where they stand. POLL WATCHERS The Republican National Committee in November reached a settlement in a lawsuit against officials in Clark County, Nevada, that requires election officials to release poll workers’ partisan affiliations. The party filed…