The Colorado Senate race appears headed to becoming one of the cycle’s most expensive in terms of party spending, as both Democrats and Republicans are dumping in millions in order to pull out a victory.

The National Republican Senatorial Committee has now spent more than $1.6 million in independent expenditures, according to Federal Election Commission records. The NRSC has aired three TV ads targeting Democratic Sen. Michael Bennet, the most recent of which launched Wednesday.

The Democratic Senatorial Campaign Committee has spent more than $4.4 million on Bennet’s behalf this year. The DSCC has so far aired six general election TV ads against his Republican challenger, Weld County District Attorney Ken Buck.

Outside groups have also flooded the airwaves. For example, American Crossroads, the 527 group founded by GOP strategist Karl Rove, dropped another $768,000 this week on TV advertising, increasing its total spending in the state to more than $2.5 million.

With early ballots being mailed to more than half the state this week, the push for votes is on.

“It’s total war,” said independent Colorado pollster Floyd Ciruli. It’s gotten “pretty nasty,” he said, and with three weeks to go, “I don’t think we’ve seen the whole show here.”

Some Republican moderates in the state still say former Lt. Gov. Jane Norton, who lost to Buck in the August GOP primary, might have given the party a better chance to win in November. It would have been more difficult to portray her as extreme, they say, which the DSCC and Bennet continue to do against Buck.

But most polls have shown the margin of the high-profile race within just a few points, with Buck usually holding the edge. A DSCC-sponsored poll in late September found Bennet up 2 points, while other public polls conducted around the same time showed Buck ahead by 5 points.

One strategist said this race appears to be more of a grudge match with national implications between the two parties, rather than a battle between two unique personalities.

“The Senate race I find to pretty much be proxies,” said Eric Sondermann, a Colorado-based independent political analyst. “Bennet is a proxy for the generic Democrat and Buck is a proxy for the generic Republican. I think you could have Smith versus Jones, and the margin would be pretty much the same.”

In a strong year nationally for Republicans, that’s a good sign for the GOP.

“The NRSC will invest whatever means necessary to help Ken Buck win,” NRSC executive director Rob Jesmer said in a memo this week.

The DSCC is doing the same there as well. “They definitely think they can win it by a point or 2, and they’re staying right on it,” Ciruli said.

In other states, however, that’s not necessarily the case, as the polls move in one direction or the other.

In Missouri, for example, the DSCC just canceled two weeks of advertising time, The Hotline reported Friday. The state had been seen by the committee as its best pick-up opportunity among Republican-held open seats, with Secretary of State Robin Carnahan touted as a top-tier recruit.

The committee cut a $335,000 check on Tuesday for last week’s media buy. With that disbursement, the DSCC has now spent more than $2.2 million on behalf of Carnahan.

But polling has shown the substantial investment has not paid significant dividends.

While a DSCC poll released on Sept. 24 showed Rep. Roy Blunt (R) ahead by just 4 points, two public polls released in the last week pegged Blunt’s lead between 8 and 13 points.

The DSCC has also been forced to go on the air in Connecticut and West Virginia — two unexpected battlegrounds that could make the difference in which party holds the majority. The NRSC has gone up with an ad in West Virginia, but with Connecticut Republican Linda McMahon’s personal wealth, the committee has not needed to spend there.

The NRSC is still not up in Pennsylvania, either, where polls show former Rep. Pat Toomey (R) leading Rep. Joe Sestak (D). The DSCC has spent heavily there on Sestak’s behalf.

Washington is another state where polls show the race neck-and-neck, and both committees are heavily invested. As of Friday, the DSCC had so far spent just less than $400,000 in the state this year. It put down an initial reservation of $2 million in TV time.

The NRSC launched its first ad there this week. It’s now spent about $540,000 of the $3.5 million in TV time it has reserved.

With just weeks to go, both parties will continue to move money around to races where it can have the most impact. The DSCC reported having just less than $23 million in the bank at the end of August, while the NRSC had roughly $24.5 million.

In Colorado, strategists say it’s clear how much of a focal point the state has been already, with heavy spending by both the committees and outside groups.

“The airwaves are pretty much blanketed right now,” Sondermann said. “The amount of ads getting thrown in Michael Bennet’s face is pretty astounding. There are so many of the 527s on the Republican side — American Crossroads, Americans for Prosperity, Club for Growth — on top of the NRSC.”

With early voting beginning this week and both parties well represented on the airwaves, Democratic strategist Michael Stratton said field and turnout operations could make the difference in the race.

“I’ve seen numbers and heard from Republican consultants that Bennet is up by 2,” Stratton said. “I would say it’s very much a tossup, and it probably comes down to the ground game that either campaign has.”