According to PoliticalMoneyLine.com:

Federal lobbying of the legislative and executive branches totaled $1.2 billion ($1,201,255,222) during the last six months of 2005. This is the first period lobbying expenditures have averaged over $200 million a month. For all of 2005 the total spent was $2,363,102,190.

Lobbying by health care interests led the pack ($183,324,757 spent in the last half of 2005), just as it has for the last 10 or so years.  That might have something to do with the fact that government purchases about half of all health care in the United States and controls the other half indirectly.

The American Medical Association was among the top five organizational spenders ($9,720,000 spent in the last half of 2005) in part because they successfully lobbied to block Medicare payment cuts, which had already been enacted into law and were scheduled to take effect this year.  That would be the third or fourth year in a row that providers have staved off those payment cuts.

Jagadeesh Gokhale and I have a theory.  It is that politicians have no intention of reducing how much Medicare pays providers, but instead use the threat of payment cuts to extract political contributions from doctors and hospitals.