Well, just what does that mean?
Actually unless you vote Progressive Alliance, not much. Recent polls indicate a trend to not vote in favor of the president's policies by about 15%. So republicans can expect an approximate 15% decrease in the vote they received before. So if they won by about 5% they can expect to lose by about 10%. The vast majority of those votes will go to the democrat. So very little changes because generally there is very little difference between a republican and a democrat.
In order to REALLY throw the bums out, voters should consider voting for either the Green or Libertarian on that ballot, if there is one. If there is one and not the other, the choice is simple. If there is both on the ballot, then the choice becomes more difficult. Here is where there is a need for a Progressive Alliance coordinating committee. That committee could make a recommendation as to which it would be better to vote for. So, throw the bums out! Please!