AUGUSTA, Maine — The national Republican and Democratic parties have largely withdrawn their advertising efforts in Maine’s Senate race, according to Federal Election Commission records and news reports, suggesting that Republicans see better victory prospects elsewhere and that Democrats are confident in independent Angus King’s chances of winning next week.

The National Republican Senatorial Committee and the Democratic Senatorial Campaign Committee have been some of the most prolific outside advertisers in the race for Maine’s open U.S. Senate seat, which has attracted nearly $7 million in spending from outside groups on TV and radio advertising, phone calls and mail pieces.

The Republicans’ Senate committee, however, hasn’t reported any new spending on Maine Senate advertising since Oct. 5, according to the Federal Election Commission. The Democratic Senatorial Campaign Committee made its last expenditure in the Maine race on Oct. 19.

The National Republican Senatorial Committee spent $1.34 million on anti-King advertising throughout much of September and October while the Democrats’ Senate arm has poured $1.48 million into ads opposing Republican nominee Charlie Summers, Maine’s secretary of state, since the start of October.

Spokesmen for neither organization responded to requests for comment Monday.

Politico reported Thursday that Republicans had gone off the Maine airwaves. The Daily Caller, a Washington, D.C.-based website, reported Monday that Democrats had done the same.

While the two major parties have dropped their Maine Senate advertising, there’s still no shortage of outside ads in the Maine Senate contest.

Crossroads GPS, a 501(c)(4) nonprofit group founded by former George W. Bush adviser Karl Rove, last week invested $344,000 in a second ad attacking King. Crossroads has now spent $667,000 on the six-way Maine Senate contest.

On King’s side, the 501(c)(4) nonprofit group Americans Elect continues to spend on the former governor’s behalf. As of Monday morning, the organization had spent $1.42 million on TV advertising and mail pieces promoting King and opposing Summers. That organization had raised $1.75 million from three donors — New York City Mayor Michael Bloomberg, Americans Elect founder Peter Ackerman and San Francisco investor John Burbank — specifically to aid King.

The onslaught of outside advertising started at the end of July when the U.S. Chamber of Commerce launched the first of three ads that attacked King in an effort to boost Summers. Since then, nine other outside groups have spent money on the race.

Through September, outside groups had spent virtually all of their money on ad campaigns attacking King in an effort to boost Summers. But the Democratic Senatorial Campaign Committee and King allies started making up the difference at the start of October and have spent more aggressively than Republican groups in recent weeks.

As of Monday morning, King opponents had spent $3.79 million, according to an analysis of Federal Election Commission data. His allies had spent $3.12 million.

While total outside spending on the race has grown by 47.5 percent since mid-October, spending by King’s allies surged 90.4 percent, compared to 24.5 percent for Summers’ boosters, according to an analysis of Federal Election Commission data.

Polling in the race has been limited in recent weeks, and polling data at the end of September showed a variety of results.

The last public poll — conducted Sept. 24-28 by Portland-based Pan Atlantic SMS Group — showed King with a 26-point lead over Summers. However, a Rasmussen Reports survey conducted Sept. 25 showed a 12-point lead for the former governor.

Meanwhile, Republicans focused on an internal poll conducted around the same time — Sept. 24-25 — for the National Republican Senatorial Committee that showed King hanging onto a much slimmer, four-point lead over Summers.