As Congress decides this week – the deadline is Thursday – which form of special exemption from Obamacare they are going to give their staff (the Administration's August directive provides both a loophole to either fully exempt some staff from ObamaCare's requirement that they go on the exchanges, or else puts them on the exchanges but then gives them a special subsidy from the cost, unlike any other American), they need to remember that both forms are still carve-outs from the law and special treatment for themselves, and a "silver bullet" issue at the ballot box.

How can we speak so certainly of the electoral power of the issue? Because earlier this month, in New Jersey's special election for the U.S. Senate, Independent Women's Voice conducted a message test to see just how much the issue moved voters – and move them it did.

First, the context: In one corner stood Democratic nominee Cory Booker, the popular Mayor of the state's largest city, with high and favorable statewide name ID and a campaign war chest to make others envious. In the other corner stood GOP nominee Steve Lonegan, a twice-failed candidate for Governor who had a rabidly intense but small statewide following in a state that hasn't sent a Republican to the U.S. Senate since Nixon went to China.

On paper, it was no contest. And in the end, Booker won by double digits, as virtually all analysts had predicted from the start of the contest.

But that just makes the results of the IWV message test that much more interesting.

To test the power of the issue, after first leaving out a demographically similar control group of 30,000 households, during the final days of the campaign IWV sent two simple robocalls into every household with a likely voter who had a land line, where "likely voter" was defined as a voter who had voted in at least two of the four preceding statewide general elections. This gave us a rather broad universe – there were more than 450,00 households with a Democratic voter who fit that profile, more than 200,000 with a GOP voter who fit the profile, and more than 130,000 with an Unaffiliated (read: Independent) voter who fit the profile.

The recorded messages were simple: President Obama gave Congress a special exemption from ObamaCare, shielding its Members and their staffers from having to purchase insurance on the exchanges without benefit of employer subsidies, like anyone else going onto the exchanges, and Steve Lonegan opposed that exemption, while Cory Booker had remained silent on the issue. The recorded message then suggested, "When you're considering your vote in next Wednesday's election, remember – a vote for Steve Lonegan is your chance to tell Congress: No Washington Exemptions."

We then conducted a poll on the day after Election Day. We surveyed 300 voters drawn randomly from the group that had received the phone calls, and another 300 voters drawn randomly from the control group of 30,000 households we had deliberately left out of the communications program so they could serve as a control. The margin of error for each survey was +/- 5.6 percent.

The two groups were remarkably similar – voters in the test group identified themselves as 25 percent GOP, 56 percent Democrat, and 16 percent Independent, while voters in the control group identified themselves as 24 percent GOP, 57 percent Democrat, and 14 percent Independent. Similarly, when we asked the survey respondents to identify themselves on an ideological scale, 28 percent of the test group identified themselves as liberal, 42 percent as moderate, and 25 percent as conservative, while in the control group the numbers were 27 percent liberal, 43 percent moderate, and 23 percent conservative.

The first check on the power of the issue was the ballot test. In the control group, Booker defeated Lonegan by a whopping 60-24 percent, a margin of +36 percent, with 16 percent refusing to tell us for whom they voted. But in the target group, Booker's lead was cut by more than half, shrinking to 50-33 percent, a margin of just +17 percent, with 17 percent refusing to tell us.

(Note: On Election Day, Booker won by a margin of 55-44 percent. It is highly likely that the bulk of those voters who refused to tell the pollster for whom they voted actually voted for Lonegan, but they were too embarrassed, or upset, to share that information with a pollster on the day after their favored candidate lost by such a wide margin.)

Comparisons of the cross tabs are instructive: In the control group, Republicans voted 73-9 percent for Lonegan, with 18 percent refusing to tell us; Democrats voted 83-7 percent for Booker, with 11 percent refusing to tell us; and Independents voted 55-19 percent for Booker, with 26 percent refusing to say. But among the voters in the test group, Republicans voted 80-8 percent for Lonegan, with 12 percent refusing to say; Democrats voted 74-12 percent for Booker, with 14 percent refusing to say; and Independents voted 39-39, a dead heat, with 22 percent refusing to tell us for whom they voted.

Put another way, Lonegan's strength among Republicans grew from +64 percent to +72 percent; Booker's margin among Democrats dropped from +76 percent to +62 percent; and Booker's lead among Independents evaporated entirely, moving from +36 percent to a dead heat.

Voters were then asked if one of the top three reasons they voted the way they did was because voting for Lonegan would send a message of opposition to the special exemption for Congress? In the control group, only 42 percent agreed that their vote was a way of sending a message; but in the test group, that number rose to 50 percent.

This overall halving of Booker's victory margin – and, particularly, the movement among Independent voters – is especially remarkable given that more than 90 percent of the voters we surveyed said they had made up their minds on the election before we ever communicated with them. That is, less than 10 percent of the voters in the test group were even open to changing their vote by the time we communicated the "no Washington exemption" message.

Politicians of both parties have tried hard to avoid having a clean vote on the Vitter-DeSantis legislation which would undo such special treatment. But whether Congressional offices stay on their present plans or receive a special subsidy for their costs on the exchange, voters — particularly as the stories mount of dropped coverage and radically increased premiums — will have no patience with it.

Congress has three choices: First: go into the law with no special favors and endure it as millions of Americans have to; second: delay the mandate and associated taxes for a year, while allowing insurance companies to again offer the policies they have had to cancel, so that everyone, including themselves can keep the policies they liked; or third: take advantage of special treatment — no Vitter, no delay — and face the wrath of voters in 2014. Let's hope they make the smart decision.

Heather Higgins is president and CEO of Independent Women's Voice. William W. Pascoe III consults on political strategy with IWV.