Up to eight Senate Democrats could find themselves under attack by Americans for Prosperity this election cycle, as the advocacy group looks to maximize negative reaction to the implementation of the Affordable Care Act ahead of the 2014 midterms.

“We want to hold accountable six to eight senators,” AFP President Tim Phillips said in an interview. “When a senator is facing re-election, it does focus them on their voting record and it does make them more attentive to how each individual vote impacts their political future.”

Phillips's group, backed by billionaire brothers Charles and David Koch, has already spent the bulk of $30 million this cycle targeting both incumbent House and Senate Democrats in vulnerable seats on their past support for Obamacare.

So far, five incumbent senators have seen ads run in their states that seek to tie them to the president’s signature law: Democrats Kay Hagan (N.C.), Mark Pryor (Ark.), Mary Landrieu (La.), Mark Begich (Alaska) and Jeanne Shaheen (N.H.). Phillips said the unpopularity of the Affordable Care Act could put  races in Virginia, Colorado and Minnesota in play. AFP has also run ads against Democratic challengers in races for open Senate seats in Michigan and Iowa.

“We’re going to continue to expand, that’s the amazing thing about Obamacare, is that it’s causing more and more states politically to come into play,” he said."The rollout last fall offered the best opportunity to educate and talk about what Obamacare meant for individual Americans and we wanted to make sure we were in the arena while this roll out was occurring. And so it was an intentional thing to do and it’s not over."

Phillips declined to say exactly how much the group would spend in the coming months, saying only, “it’ll be substantial” and that it is determined to expand the field.

In a January NBC-WSJ poll, 34 percent of those surveyed said the health-care law was a "good idea" while 48 percent said it was a "bad idea."

The early deluge of money has shocked some Democrats who have come to expect the onslaught of attack ads from outside groups later in the cycle.

Both the House Majority PAC and the Senate Majority PAC have launched ads to combat the attacks, highlighting AFP’s Koch connection and the efforts of Democratic lawmakers to fix the health-care law.

Jeff Simon contributed to this report