This was ostensibly a vote on a motion to table (kill) a "motion to commit" (i.e. an amendment) by Sen. John Cornyn (R-TX) that would have would have eliminated a provision in health care reform legislation placing a 3.8% tax on investment income for those making more than $200,000 per year. (Retirement investments were exempted from this tax.) The measure Cornyn sought to amend was a “companion bill” making a number of changes to health care reform legislation already signed into law by President Obama. The underlying context was that Republicans were trying to attach amendments to the companion bill in order to send it back the House, where it had passed by a narrow margin. CNN reported that Republicans had chosen to offer a slew of amendments in order to “undermine the measure,” while the Associated Press characterized the amendments as “a final drive to thwart President Barack Obama's health care remake.”

If passed, a motion to commit sends the legislation back to committee with instructions to amend the legislation as specified. 

Sen. John Cornyn (R-TX), the sponsor of the amendment, urged the Senate to support it: "It [the tax] will discourage savings and investment and decrease the standard of living for millions of Americans. Simply put, increasing taxes on investment income and savings income is a job killer."

Sen. Max Baucus (D-MT) argued the amendment would primarily help the wealthy: "…This is an honest, straightforward amendment which is concerned about people making more than $200,000….it is only concerned about people making more than $200,000 in income."

After the House and Senate both passed their respective health care reform bills, the two chambers had intended to reconcile those two bills into a final package. After the House and Senate passed that final package, it would have been sent to President Obama, who would have signed it into law. Sen. Scott Brown (R-MA), however, won a special election to replace the late Sen. Ted Kennedy (D-MA) before the final health care bill could be brought up for a vote. Brown's victory gave Republicans 41 votes in the Senate, leaving Democrats with 59 members – one vote short of the 60 votes they needed to defeat a unanimous Republican filibuster against the final health care bill. 

In order to pass comprehensive health care legislation without a 60-vote majority in the Senate, Democratic leaders devised a plan in which the House would pass the Senate health care bill (H.R. 3590), thereby enabling the president to sign it into law. The House would then pass a separate companion bill (H.R. 4872) to make changes to the Senate health measure under a process known as "budget reconciliation." Bills considered under budget reconciliation cannot be filibustered under Senate rules. This process allowed the House to make changes to Senate-passed health care legislation without sending the entire health bill back to the Senate, where it could have been filibustered indefinitely.   The companion bill incorporated changes to the Senate health care legislation desired by House Democrats. The House passed the companion measure, and sent it to the Senate, where Democratic leaders hoped to defeat all amendments -- thereby avoiding a second vote in the House on a substantively changed bill; a vote that Democrats might have lost given the already tight margin when it was voted on the previous week.

The Senate tabled (killed) the Cornyn motion to commit by a vote of 52-46. 52 Democrats voted "yea." All 40 Republicans present and 6 Democrats voted "nay." As a result, the Senate rejected an amendment Democratic leaders feared could have torpedoed the entire companion health care bill and would have eliminated a 3.8% tax on investment income for those earning over $200,000 per year.