Primary elections: Seven states to watch
Democrats will be watching the Republican contests closely, hoping for additional upsets by tea party-backed candidates. Democrats hope the Republicans will be saddled with unelectable candidates. Republicans are looking to ride a wave of voter anger over the sputtering economy and politics-as-usual to regain control of Congress.
The competition between traditional Republicans and their tea party counterparts is particularly strong in Delaware, New Hampshire, and New York.
Rhode Island, Massachusetts, Wisconsin, and Maryland also hold primaries Tuesday.
As reported yesterday, O'Donnell has surged ahead of nine-term Congressional incumbent Mike Castle in Delaware's Republican Senate primary, much to the distress of the party's leadership.
O'Donnell has the support of former Alaska Gov. Sarah Palin as well as tea party activists.
New Castle County Executive Chris Coons has no opposition for the Democratic nomination.