Democrats are not waiting for the general election to officially start in the two most competitive states yet to hold a Republican Senate primary.

Democratic outside groups are playing an active role in defining the GOP candidates in Missouri and Wisconsin, and if they’re lucky, perhaps even helping push their preferred general election opponent ahead. Republicans are targeting both Democratic-held seats in their quest for the Senate majority.

“With the rise of super PACs, you’re going to see more and more of these sorts of tactics, but it’s really nothing new,” Democratic media consultant Mark Putnam said. “It’s just easier for a super PAC to do this because it’s not as transparent as when a Democrat or Republican tries to influence a primary on the other side of the aisle.”

Majority PAC, a Democratic-aligned group working to keep the party’s Senate majority, launched an ad Tuesday against Wisconsin Senate candidates Tommy Thompson and Eric Hovde, who have led in recent polling of the GOP primary.

The ad came two weeks after one from the independent expenditure unit of EMILY’s List, which is supporting Rep. Tammy Baldwin (D) in the Senate race. Both ads went directly after Thompson and Hovde, ignoring the other leading candidate in the race, former Rep. Mark Neumann, who trails well behind the two frontrunners in recent polling and is viewed as less of a threat in November.

Nearly the same thing happened in Missouri, where it’s clear Democrats would rather have Sen. Claire McCaskill face Rep. Todd Akin in November than either of his top Republican primary opponents, businessman John Brunner or former state Treasurer Sarah Steelman.

For McCaskill, Democrats’ most vulnerable incumbent, the strategy could be vital to her winning a second term, with the goal being to either land a less competitive opponent or stifle any momentum coming out of the primary for the eventual GOP nominee.

Majority PAC recently began airing a TV ad in Missouri challenging Brunner’s business record. A trio of ads from the McCaskill campaign followed last week, with each appearing to attack her potential opponents and define them for the general election.

But, as The Hotline noted last week, McCaskill’s ad targeting Akin clearly could also have the effect of boosting the Congressman’s prospects in the GOP primary by calling him “a crusader against bigger government” and “Missouri’s true conservative,” while highlighting his “pro-family agenda.”

While the ads could help define the GOP nominee coming out of the primary, Putnam was skeptical that a Democratic ad could have much of an effect on a GOP primary outcome, or vice versa.

“Regardless of whether it’s a candidate or a super PAC funding the ads, it’s a mixed bag as to how well playing across the party aisle really works,” Putnam said. “Primary voters are usually better informed and can often see through ads like these.”