It’s getting harder for Democrats to blame Tea Partiers for blocking a debt ceiling deal, now that all 53 Senate Democrats (and independents) have signed a letter saying they will not support Boehner’s plan. But Sen. Harry Reid gave it a final try this morning:

“A small group of radical Republicans who don’t represent mainstream America… have refused to move one inch towards compromise,” said Reid.

“There has been a spate of these members of the House of Representatives that have said they would rather see the nation default on its financial obligations than cooperate,” he continued.

This argument won’t be able to hold up for much longer. If Boehner’s plan passes the House and Democrats don’t accept some variation of it, then the responsibility for default will lie squarely on their shoulders. Marc Thiessen writes in the Washington Post:

Senate Majority Leader Harry Reid declared the Boehner proposal “dead on arrival” in the Senate, but this more accurately describes his own plan. Reid does not have the votes to overcome a GOP filibuster in the Senate — and if Reid cannot pass his plan, then the Boehner plan is the only game in town. If the House passes the Boehner plan, and Reid’s plan is stalled, Senate Democrats will face a choice: Pass Boehner’s bill and send it to the president or take responsibility for causing a government default. Here’s my prediction: They will pass it. And Obama will sign it.

With default looming, I’ll even wager that his senior advisers will “recommend” he do so.

Senate Democrats have boxed themselves into a corner on this. By mounting such a strong opposition to Boehner’s plan, they’re actually helping to unify House Republicans. There may be an out if Sen. Mitch McConnell and Vice President Biden – who are still in discussion – come up with a compromise deal by tomorrow.