Voters in Ohio, Indiana and North Carolina begin a month-long sprint tomorrow with multiple primary elections, including some of the most contested Senate seats and special elections for two House races. It’s kind of a rolling, mini-general election over the next month.

US Senate seats are up for grabs in two of the three states, and in North Carolina, Republican Richard Burr is seen as vulnerable.

In Ohio, George Voinovich is retiring from the Senate. Rob Portman, George Bush’s former budget director, will be the Republican nominee. On the Democratic side, Lt. Governor Lee Fisher has been pulling away from Secretary of State Jennifer Brunner in recent weeks, thanks to a cash advantage and more advertising. The DSCC reportedly spent money on Fisher’s side, though that has not been corroborated. Brunner, reflecting the testy primary, vowed not to campaign for Fisher if she loses. The general election is seen as a toss-up.

In Indiana, Evan Bayh left the race before any replacement could get into the primary, and party leaders are widely expected to choose Rep. Brad Ellsworth as the nominee for November. Among Republicans, former Senator Dan Coats does not have majority support, but a split on the more conservative side of the ledger looks to give him a victory. Coats would start the general election with a pretty robust lead over Ellsworth.

In North Carolina, there are three major candidates attempting to knock off Richard Burr. The DSCC made their preference known a while back with former state Senator and Iraq war vet Cal Cunningham, but Secretary of State Elaine Marshall is better-known, and she has been expanding her lead in the closing days. However, a law in North Carolina says that the primary winner must hit 40% to avoid a runoff, so it’s plausible, if not likely, that we’ll see one between Cunningham and Marshall.

There are some scattered House elections with primaries as well, including Larry Kissell facing a progressive challenger in North Carolina.

This just begins the May primary season. The unusual convention process in Utah could end Bob Bennett’s Senate career on May 8. Nebraska and West Virginia have largely uncontested primaries on May 11, but May 18 features a blockbuster: the Specter-Sestak primary in Pennsylvania, the Halter-Lincoln primary in Arkansas, and contested races on both sides in Kentucky. In addition, there’s a special election in PA-12 on May 18 and one in HI-01 on May 22. Plus, if you like international elections, Britain’s general vote is May 6.