Sen. Mark Begich (D-Alaska) and his backers have just bought $6.4 million in TV slots for his reelection campaign ads. (2013 file photo by Marc Lester for The Washington Post)

Alaska is a state where fortunes have been made quickly. Gold and oil prospectors have come to the Last Frontier with only the clothes on their backs and left as wealthy men.

This year, a different kind of fortune will be made: Owners of local television stations are raking in millions of dollars in political advertisements. And for all the hand-wringing about outside conservative interests pouring early money into key races, in Alaska it’s Democrats who have fueled a more traditional advertising boom.

Sen. Mark Begich (D) and two groups backing his campaign have purchased a combined $6.4 million in television time for the final sprint between Labor Day and Election Day, a crucial stretch when voters begin to tune in and pay attention to candidates seeking their votes.

The Democratic Senatorial Campaign Committee on Monday purchased at least $3 million in advertising beginning Sept. 23 and running through Nov. 4. That money will buy about 1,000 gross ratings points per week in the Anchorage and Fairbanks media markets. Put Alaska First, a super PAC funded largely by the Senate Majority PAC, has plunked down $3.2 million over the same period, worth another 1,000 gross ratings points in those two markets. Both committees are buying smaller amounts in the Juneau market, which has just one network television station, an ABC affiliate.

Begich’s campaign has started making its own reservations, too, buying $230,000 in ads scheduled to run over the final three weeks before Election Day at about half the levels of the outside groups.

A gross ratings point measures the percentage of an audience likely to see a given ad one time, so 100 points means every viewer is likely to see an ad once. All told, Democrats have bought more than 29,000 gross ratings points over the campaign’s final two months, meaning the average Alaska viewer would see 290 commercials touting Begich or slamming the evenutal Republican nominee.

Buying television time early has its advantages because the advertising market is finite: There are only a limited number of television spots available for purchase, and costs begin to rise when more organizations start bidding for scarce airtime. By plunking down money now, campaigns and outside groups are guaranteed access to the airwaves, and to specific time slots that have the greatest impact.

But the Democratic ad buys also underscore a problem Republicans face: Alaska has one of the latest primaries in the country. Voters won’t pick a Republican nominee until Aug. 19, just eleven weeks before Election Day. That means the Republican nominee for the Senate seat — at the moment, most observers say former state attorney general Dan Sullivan has the edge against Lt. Gov. Mead Treadwell and 2010 candidate Joe Miller — will have a relatively short amount of time to restock his war chest and launch his own television ads.

Outside conservative groups are likely to pick up the slack in the meantime. The two Crossroads groups have spent money on advertisements that have already run, as have groups like the Chamber of Commerce and the Koch brothers’ groups Americans for Prosperity and Freedom Partners. But none of those groups have bought late television time like Democrats have — yet.