Primaries 2010: Last Chance for Tea

WASHINGTON, Sept. 14, 2010— -- Conservative Tea Party candidates will try to pick off two more favorites of the Republican establishment in the last primaries before election day as voters in seven states and the District of Colombia head to polls .

The most competitive and consequential races are Republican primaries in New Hampshire and Delaware, where insurgent conservatives are trying to kick establishment candidates out of the running. The races are distinct and place Tea Party candidates on both sides of national figures like Sarah Palin.

But which candidates win Tuesday could determine if Republicans have a chance to take control of the Senate in November.

In Delaware, moderate Republican Congressman Mike Castle is getting a spirited challenge from Sarah Palin-and Tea Party backed perennial GOP candidate Christine O'Donnell. Castle had been favored to easily with the Republican nomination and was also ahead in polls to win the seat in November.

But Castle is one of the most moderate Republicans on Capitol Hill, breaking with his party on issues like climate change. O'Donnell has come on strong with help from the conservative party base.

Read ABC's coverage of the Delaware race here.

And watch Jonathan Karl's Delaware Campaign Notebook here and here.

One recent poll showed the race in a dead heat, which sent alarm bells through Washington. A loss by the Republican in the general election would be a huge blow to GOP chances to win the seat and perhaps nail shut their chances to take control of the Senate.

The race is for the seat once held by Vice President Biden, who held if for more than thirty years. Unlike Alaska, where conservative lawyer Joe Miller shocked Republicans by defeating sitting Sen. Lisa Murkowski in last month's primary, Delaware is a very blue state and Democrats think they have a strong candidate in county executive Chris Coons.