Thanks in large part to the shifting preferences among tea party aligned Republicans, there has been little consistency in the top tier of candidates in Washington Post-ABC News polls since July.

Mitt Romney has been the steadiest presence, at or near the top in three straight Post-ABC polls. But there have been seismic movements for other campaigns. In July, after a successful Iowa straw poll, Michele Bachmann (R-Minn.) occupied second place after Romney. By September, Texas Gov. Rick Perry had vaulted to first place, and Bachmann had faded. This month, Perry cooled off and businessman Herman Cain entered the top tier.

The common denominator in these shifts has been rapidly changing preferences of tea party supporters, particularly those who who support the political movement “strongly.”

In July, Bachmann won 28 percent of the vote among Republicans and GOP-leaning independents who strongly support the tea party. Since then, her support in the group has dwindled to 9 percent. Perry has seen the most dramatic changes, winning 45 percent among the strong tea party crowd in September, just after officially joining the race. A couple of shaky debate performances later, and Perry has dropped all the way to 10 percent.

Cain has been happy to pick up the pieces from Perry, moving from 5 percent in September to 30 percent among strong tea party supporters this month. Romney has been the most consistent across this time, going from 21 percent to 15 percent and back to 19 percent among strong tea party supporters in Post-ABC polls since July.

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