The Democratic Senatorial Campaign Committee is rolling out a new Web site today: KochAddiction.com. The website’s goal is to spell out which Dem Senate candidates are being targeted by the Koch-backed Americans for Prosperity, and what the Koch brothers’ agenda for the country really looks like.

This is part of a broader strategy Dems have developed to tie GOP Senate candidates to the Koch brothers. Dem Senate candidates have hit GOP foes as beholden to the Kochs, and Harry Reid has attacked them on the Senate floor, hoping to bait Republicans into leaping to their defense (which they have done).

The real goal of this strategy has not been adequately explained. It is widely depicted as little more than an effort to tar Republican candidates with faceless plutocrats. Republicans paint it as a desperate effort to gin up the Dem base and to distract from struggling Dem candidates.

But there’s something more complex going on here. The “Koch addition” approach is rooted in a strategic imperative Dems face: How can they create a framework within which voters will believe what they are saying about the real policy agenda Republicans are campaigning on?

A recent Post/ABC News poll found that Dems hold a real advantage on many issues, but nonetheless hold a disadvantage in Senate races. Polls show majorities agree with Dems on specific policies they’re campaigning on — the minimum wage; unemployment benefits; etc. But that’s bumping up against the structural reality that Senate control will largely be decided in seven states carried by Mitt Romney in 2012.

The challenge Dems say they face is to get voters to focus on actual positions held by GOP candidates, and on the fact that those positions are not in their economic interests. Why do these candidates oppose raising the minimum wage, or extending unemployment insurance, or expanding Medicaid, all of which would benefit so many people in the states they would represent? Republicans may claim a legitimate rationale for these positions, but the question is, how do you get voters to focus on the fact that these are really their positions?

Or, on local issues: Why does GOP candidate Tom Cotton of Arkansas oppose the farm bill, which many others say would benefit the state? (AFP opposes it.) Where are the GOP Senate candidates in Alaska on the closing of a refinery in that state, which was criticized by many local officials? (Koch companies own it.)

Dems hope to focus voters on these actual positions by painting candidates as beholden to an agenda held by outside interests. The Koch brothers are a proxy for special interests in general, an easy-to-understand concept designed to create a narrative framework within which voters might reach the general conclusion that GOP candidates’ priorities aren’t in their states’ interests; they are serving something — or someone — else.

This is similar to the Dems’ Bain strategy of 2012. This was widely seen as nothing more than an effort to paint Romney as a heartless plutocrat. In reality, the goal was to create a framework within which voters could be persuaded of his actual policies and priorities, which research had shown voters simply weren’t prepared to accept.

The same thing is going on here. Will it work? Republican structural advantages may well prove very difficult to overcome. But it’s at least worth appreciating what Dems are actually up to.

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.