Verb (used without object), : His tendency to vacillate makes him a poor leader.    From Dictionary.com. 

So Raedwald is usually seen as a vacillator under his wife's thumb, a weathervane who tried to have his cake and eat it.    From Wordnik.com.  [Five historical figures] Reference

Pat Quinn as a waffler, a vacillator, a flip-flopper.    From Wordnik.com.  [The Full Feed from HuffingtonPost.com] Reference

Lieberman has been a political vacillator all ofhis life.    From Wordnik.com.  [AlterNet.org Main RSS Feed] Reference

Lacking a core pillar of ideology, Carter proved to be a micromanager and a constant vacillator.    From Wordnik.com.  [YID With LID] Reference

One vacillator isn't the end of the world. maddyboom (38 posts) on March 24, 2009 - 3: 37am. pick me pick me!!.    From Wordnik.com.  [AfterEllen.com - Because visibility matters] Reference

And, all along, he had been regarding himself as the weakling, the vacillator, when it was he who had held out the longest!.    From Wordnik.com.  [Phantom Wires A Novel] Reference

He was a vacillator.    From Wordnik.com.  [Dreams of Steel]

But I do despise a vacillator, and I am one.    From Wordnik.com.  [The Colossus A Novel] Reference