Another major primary day is upon us as voters in 11 states decide their party’s candidates in November. Key toss-up races we’re watching are all Republican primaries to challenge Democratic incumbents in the fall including: The Nevada Senate seat, Nevada’s 3rd Congressional District and Virginia’s 2nd and 5th Congressional Districts. Arkansas will also hold a runoff election for the Democratic senate candidate as incumbent Blanche Lincoln fights a strong challenge from Lt. Gov. Bill Halter.

In Nevada, GOP challengers to incumbent Democrat Senator Harry Reid include businesswoman Sue Lowden, businessman Danny Tarkanian, banker John Chachas, and former Nevada assemblywoman Sharron Angle. In the state’s 3rd Congressional District, freshman incumbent Dina Titus will be challenged by one of eight GOP candidates; frontrunners include Joe Heck, Brad Lord-Leutwyler, and Robert Lelie Lauer.

In Virginia’s 2nd Congressional District, incumbent Glenn Nye will be one of 10 GOP challengers: Ben Loyola, Ed Maulbeck, Bert Mizusawa, Scott Rigell, Jessica Sandlin and Scott Taylor. In the state’s 5th Congressional District, incumbent Tom Perriello will face one of the eight GOP candidates; the frontrunner is state senator Robert Hurt.

Other states holding primaries today include California, Iowa, Maine, Montana, New Jersey, North Dakota, South Carolina and South Dakota.

• Danny Tarkanian, who hopes to unseat Senate Majority Leader Harry Reid (D-Nev.) in November, is boasting of recent polling numbers in an invitation to a fundraising luncheon at La Loma on the 19th.  Tarkanian is part of a crowded field of Republicans challenging the Reid, who is widely seen as vulnerable thanks in large part to his championship of health care reform.
• Sen. Michael Bennet (D-Colo.), who faces a primary challenge back home in Colorado from Andrew Romanoff (who was recently passed over as a possible candidate in the governor’s race) continues to show his D.C. fundraising power with a reception, featuring Education Secretary Arne Duncan, also on the 19th. Before being tapped for the Senate seat by now-retiring Governor Bill Ritter, Bennet served as Denver school superintendent. Bennet has raised 58 percent of his cash from out-of-state; after Denver, his top two contributing geographical areas are New York and Washington, D.C. The reception is at the home of Katherine and David Bradley; Bradley is publisher of The Atlantic Monthly Magazine, where Bennet’s brother, James, is editor-in-chief.