The conservative Tea Party movement has scored two upsets in the Republican primary contests ahead of November’s mid-term elections.
Christine O’Donnell beat Congressman Michael Castle for the right to run for the Delaware Senate seat, which was once held by Democratic Vice President Joe Biden.
Former vice-presidential nominee Sarah Palin backed O’Donnell but the Republicans will not fund her campaign.
Officials fear she will put off moderate voters and hand victory to the Democrats.
The Tea Party movement wants lower taxes and spending and a smaller federal government.
Another challenger Carl Paladino won the race to stand for New York governor.
New York Congressman Charles Rangel fended off a Democratic Primary challenge despite allegedly breaching House ethics rules on more than a dozen counts.