Portland, Maine ? Two years after Democrats won a Senate seat in Michigan with a campaign targeting the high cost of prescription drugs, they turned their gaze to Maine, another state where seniors regularly go to Canada to buy cheaper pills.

Their strategy was good so good, in fact, that Republicans adopted it, too.

As a result, the issue has been muddied, and first-term Republican Sen. Susan Collins remains a strong favorite for re-election in November. She also is perhaps the year’s most prominent practitioner of politics-by-inoculation against popular issues raised by an opponent.

Sensitive issue in state

With a population that is older, poorer and closer to Canada than those of most other states, including those with competitive Senate races this year, Maine was sensitized to the prescription drug issue. And in Chellie Pingree, a former state Senate majority leader who championed Maine’s pioneering program to force reductions in drug prices, Democrats had the ideal candidate to capitalize on the issue. Pingree quickly made it her top campaign issue.

Two years ago in Michigan, then-Rep. Deborah Ann Stabenow, a Democrat, got out ahead of Republican Sen. Spencer Abraham on the prescription drug issue. He could never catch up, losing narrowly to Stabenow in what Democrats regarded as evidence of the issue’s potency.

But Collins did not make Abraham’s mistake. She took a front-and-center role in the recent Senate debate on legislation to make drugs more affordable for Medicare recipients. To Pingree’s chagrin, Collins wound up as a co-sponsor with Sen. John Edwards, D-N.C., of a compromise bill. Passed by the Senate, it aimed at getting cheaper generic drugs to market faster by limiting patent extensions for brand-name drugs.

Collins also helped push through a proposal to increase Medicaid funding for the states and supported an amendment, also adopted by the Senate, to allow “reimportation” of U.S.-made drugs from Canada, where they are cheaper because of government regulation. She even voted for a proposal by Stabenow to give legal protection to states that want to replicate the Pingree-written “Maine Rx” plan, which seeks to force pharmaceutical companies to negotiate lower drug prices for people without health insurance.

Siding with the other side

The real eye-catcher came when Collins was one of four Republicans to vote for a last-ditch effort by Democrats to pass Medicare coverage for prescription drugs, a scaled-back plan targeted mainly at Medicare recipients with low incomes and high drug costs. It fell well short of the 60 votes needed to overcome procedural obstacles.

In what Republicans angrily denounced as a distortion, the Maine Democratic Party ran a television ad accusing Collins of “siding with the big drug companies” in voting for the proposal. Collins retorted that all but five Democrats voted for it, including Stabenow and Senate Majority Leader Tom Daschle of South Dakota. Drug companies lobbied Collins to vote against the proposal, not for it, she said. Republicans ran an ad calling on Pingree to “get her facts straight.”

Regardless, the ad dispute underscores the emphasis both candidates have placed on the prescription drug issue.

“Drugs and the economy are so dominant that voters don’t want to hear anything else, and the economic issues are being fought out in the governorship race,” said Anthony Corrado, professor of government at Colby College in Maine. “It’s not clear whether either (Senate) candidate’s message has penetrated the electorate, but what is clear is that there is deep concern about the problem and the candidates reflect it.”