I may be misunderstanding your question, but there have not yet been any full Congressional votes regarding sentencing disparity.

As of 3/11/08, Barack Obama is a cosponsor of S.1711 ("A bill to target cocaine kingpins and address sentencing disparity between crack and powder cocaine.") Search Thomas by this bill number for more details, as well as links to related bills in the House and Senate and their current statuses.

In April 2007, the US Sentencing Commission released new guidelines for federal sentencing of crack cocaine offenses. On December 11, the commission voted unanimously "to give retroactive effect" to these guidelines.

The viewpoints of both Hillary Clinton and Barack Obama appear in news reports, such as:

• "Obama's caution on drug sentencing" by Derrick Z. Jackson; Boston Globe, 8/15/07
• "Obama says he would relax drug sentencing, address inequalities in justice system" by Nedra Pickler; Associated Press, 9/28/07

  [excerpt]
  "'If you're convicted of a crime involving drugs, of course you should be punished,' Obama said in a speech at Howard University's opening convocation. 'But let's not make the punishment for crack cocaine that much more severe than the punishment for powder cocaine when the real difference is where the people are using them or who is using them.'"

• "Drug Ruling Not Likely to Free Many" by James Oliphant; Chicago Tribune, 12/17/07

  [excerpt]
  "The issue has split the Democratic presidential candidates. Sen. Hillary Clinton of New York has come out against retroactivity, while Sen. Barack Obama of Illinois supports it. In a speech in September, Obama said, 'Let's not make the punishment for crack cocaine that much more severe than the punishment for powder cocaine when the real difference between the two is the skin color of the people using them.'"

• "Crack-Sentencing Reductions Decried;
  Mukasey: Gang Members Would Be Let Go" by Darryl Fears; Washington Post, 2/7/08

  [excerpt]
  "Sen. Hillary Rodham Clinton (N.Y.) said she was against making the guidelines retroactive. 'In principle, I have problems with retroactivity,' she said. 'It's something a lot of communities will be concerned about, as well.'

  "Sen. Barack Obama (Ill.) wavered. 'Even if we fix this, if it was a 1 to 1 ratio, it's still a problem that folks are selling crack. It's still a problem that our young men are in a situation where they believe the only recourse for them is the drug trade.'"

• "Where they stand on crime, death penalty;
  Differences are greater between parties than between candidates" by Bob Egelko; San Francisco Chronicle, 2/10/08