This doesn’t come as a surprise, but that doesn’t make it any easier to swallow. We’ve been saying for months that Democrats would undermine the agenda of change. Today, The Hill identifies the six main culprits in the Senate:

Half a dozen members of the Senate Democratic Conference pose the biggest threat to President Obama’s agenda, giving Senate Republicans a fighting chance to block the administration’s major expansions of government. GOP leaders have begun reaching out to these centrists, hoping they will buck their party on Obama’s two biggest initiatives: healthcare reform and climate change legislation.

Yes, the GOP leaders, who have led their caucus into minority status, hold sway over these Democrats:

Leading the pack of potential defectors are Sen. Ben Nelson, a pro-business Democrat from Nebraska; Sen. Joe Lieberman, a self-described Independent Democrat from Connecticut; and Sen. Mary Landrieu, a Louisiana Democrat who represents a conservative state. All three have expressed concerns about the core element in Obama’s healthcare proposal: a government-run insurance program that would compete with the private sector. The three also worked together this year to successfully cut more than $100 billion from Obama’s economic stimulus package. The other Democrats who are expected to voice the most serious objections to either or both of the administrations top priorities are: Sens. Evan Bayh (Ind.), Blanche Lincoln (Ark.) and Mark Pryor (Ark.).

Yes, some of those Senators cut money from the stimulus package. Smart move, since now we know (well, Krugman knew last Christmas) the bill wasn’t even large enough to begin with.

If he so chooses, Obama can use the un-filibusterable reconciliation process to pass health care reform — meaning he’ll only need 51 votes in the Senate, rather than face a 60-vote threshold needed to break an almost certain filibuster. Good thing, because weak Democrats like those above may force his hand. No doubt, we’ll be reading much more about these turncoats over the next few weeks as they try to water down both the health care and climate change bills. They all need a lot more pressure from their constituents, not less.