PORTLAND, Maine (AP) — Republican Charlie Summers is getting another television boost — the biggest yet — from the National Republican Senatorial Committee in the race to succeed retiring U.S. Sen. Olympia Snowe of Maine, an official said Tuesday.

The committee is spending $600,000 over the next two weeks on the TV campaign, said an NRSC official, who wasn't authorized to publicly discuss the matter and spoke to The Associated Press on the condition of anonymity. Maine is one of three states where the committee is currently engaged.

The U.S. Chamber of Commerce also has been a big spender on Summers' behalf, with television ads attacking independent candidate Angus King as the "king of spending."

King's spokeswoman said the TV campaign represent much of what's wrong with the current system.

"This is more out-of-state special interest money that clearly shows how broken Washington actually is," spokeswoman Crystal Canney said. "This is partisan interest money trying to tell Maine people how to vote. This is exactly what's wrong with the system."

Also in the race is Democrat Cynthia Dill, herself subject of ads from a GOP-led super PAC that urged Democrats to choose her over King. Dill denounced the ads as a cynical attempt to deceive voters.

Three other independents also are in the race.

University of Maine political science professor Mark Brewer said the Capitol Hill committee money flowing into the race is an important barometer because the committee doesn't spend money willy-nilly.

"They don't throw money around like drunken sailors on shore leave. There's got to be something behind this, giving them at least some inkling or suspicion that spending money on this race could have significant benefits for Charlie Summers," Brewer said.

The Summers campaign insists it's taking a bite out of King's sizable lead in the polls. King led the race with nearly double the support of his closest competitor in a July poll.

In that poll, King was favored by 55 percent of surveyed voters, compared with 27 percent support for Summers and 7 percent for Dill. Nine percent were undecided.

Maine Republican Party Chairman Charlie Webster insisted that King's support isn't as strong as some would suggest, describing it as "a mile wide and a sixteenth-of-an-inch deep."

"He believes in spending on programs at levels that we cannot afford," Webster said. "The country is going bankrupt and electing someone who's going to take us farther down the road to bankruptcy doesn't make sense."