Donnelly defeated state Treasurer Richard Mourdock, and Warren defeated Sen. Scott Brown in the race for the late Sen. Edward Kennedyís former seat.
Updated 9:21 p.m. | There were still several races too close to call three hours after the first polls closed and with the battle for the Senate still up for grabs.
However, WWE CEO Linda McMahonís (R) loss to Rep. Christopher Murphy (D) in Connecticut knocked ó along with Florida, Ohio and Pennsylvania ó another pickup opportunity off the map for Republicans. Every missed opportunity narrows the GOPís path to eclipse the Democratsí 53-47 majority.
Races were still too close to call in Virginia and Massachusetts, and polls in a few more important states closed at 9 p.m. They included the Tossup races in North Dakota and Arizona, two states GOP presidential nominee Mitt Romney will win easily and that were not expected early in the cycle to host competitive Senate races.
Rep. Rick Berg of North Dakota is hoping to add this state to the Republicansí column. He faced former state Attorney General Heidi Heitkamp (D) for the seat of retiring Sen. Kent Conrad (D). Rep. Jeff Flake (R-Ariz.) is looking to hold the seat of retiring Sen. Jon Kyl (R) in a competitive showdown with former Surgeon General Richard Carmona (D).
Democratsí ability to keep both races competitive contributed to the changing narrative of the Senate landscape this cycle.
Polls also closed in several other states with varying degrees of competition. In Nebraska, state Sen. Deb Fischer (R) was favored against former Sen. Bob Kerrey (D) in the race for the seat of retiring Sen. Ben Nelson (D). This was Republicansí best pickup opportunity of the cycle.
Wisconsin is another closely watched open-seat race. Rep. Tammy Baldwin (D) and former Gov. Tommy Thompson (R) were running close in late polls in a state also close in the presidential race.
Rep. Martin Heinrich (D-N.M.) was expected to hold the seat of retiring Sen. Jeff Bingaman (D). Polls for the last two months gave Heinrich a significant advantage against former Rep. Heather Wilson (R), who lost a 2008 bid for Senate.
8:11 p.m. | Polls closed at 8 p.m. in two of the most closely watched Senate races in the country, as well as two races that were late entrants to the competitive playing field.
The Republican-held seats in Massachusetts and Maine provided Democrats with their best pickup opportunities this cycle. Former Gov. Angus King (I) won the Senate race in Maine and is expected to caucus with Democrats, but the three-way general election provided for some interesting media strategies from both national party committees. The Associated Press projected him the winner shortly after 8 p.m.
In Massachusetts, Sen. Scott Brown (R) and Harvard Law School professor and consumer advocate Elizabeth Warren (D) engaged in one of the most expensive and competitive races in the country. Along with Maine, the outcome there has considerable ramifications for the GOPís majority prospects, as a loss would in turn mean the party must pick up yet another Democratic seat.