“On Dec. 24, 2009, the Democratic-controlled Senate passed President Obama’s healthcare law with a filibuster-proof 60-vote majority, triggering a massive backlash that propelled Republicans to control of the House the following year. On the Senate side, going into Tuesday’s elections, 25 senators who voted for Obamacare were already out or not going be part of the new Senate being sworn in on January.
To be sure, it isn’t fair to attribute all of the turnover in the chamber to Obamacare. Many senators voted for Obamacare and lost re-election battles in which they were hit hard for their support for the law, and other Democrats were forced to retire because they had no hope of getting re-elected given their support for the law. But in some cases — such as John Kerry leaving his seat to become secretary of state, or Robert Byrd passing away — Obamacare clearly had nothing to do with it.
Additionally, some outgoing pro-Obamacare votes were replaced by new Democratic senators.
That having been said, as of this writing, 15 Senators who voted for Obamacare either failed to win reelection or declined to run for reelection and had their seats turned over to Republicans. That number is likely to grow once the results are in from the Senate runoff in Louisiana, which Mary Landrieu is expected to lose.” - 29 senators who voted for Obamacare and won't be part of new Senate, 11/06/2014, washingtonexaminer.com
Note: The link below is to the entire article that produces the exact breakdown of the missing Senators.