Everyone agrees our health care system is unsustainable and too often unfair. At the White House health care summit, that was the only common ground between Democrats and Republicans.

Many Americans are either left-brain liberals or right-brain conservatives, with the remainder somewhere in the middle. These left- and right-brain types look at the same facts but come to different conclusions-no matter what.

This past election, something unique occurred. The independents were so frustrated with the Republicans about the Iraq war, the financial meltdown and the spendthrift ways of Congress that they swept liberals into power and apparently gave them a mandate to pass health care reform.

The liberals set about doing just that. No false advertising was involved-they crafted health care bills consistent with their campaign promises. But when conservatives erupted over the legislation last summer, they reminded many of those independent voters about their more-moderate political instincts.

It turns out that liberals needed the backing of a handful of moderate Republicans — not because they needed their votes, but because they needed their endorsements.

By August, when the raucous town meetings occurred, it became clear that liberals had overplayed their hand on health care. After election defeats in Virginia, New Jersey and, most notably, Massachusetts, as well as months of months of sagging opinion polls, Democrats tried to adjust.

There was one problem: The more that the Democratic leadership pulled the health plan toward the center, the worse it looked to everyone-liberals, conservatives and independents.

That was the backdrop as Democrats and Republicans arrived at Blair House Thursday for the health care summit – a meeting that was not so much an attempt at bipartisanship as an effort to create political cover for wavering Democratic moderates in the House and Senate.

The thinking was that if the president and the Democratic leadership managed to show that their plan was better than the comparatively thin Republican approach – and as a result win points in the public opinion polls — the moderates would perhaps feel free to vote for the big Democratic bill.

But the White House summit ended in a draw.

The Democrats talked about the substance of the bill, but the Republicans knew that the latest polls favored “starting over” and aggressively repeated that message all day. They played to the anxiety of swing voters about a huge entitlement expansion in the face of the Great Recession, as well as skepticism about the Democrats’ trillion-dollar numbers.

Now, with the session behind them, Democratic leaders and the president apparently believe they can’t go backward and that tearing up their health care bill would be admitting they can’t govern with huge majorities. Also off the table is support from moderate Republicans.

The Democrats have two options.

The first is to ignore the recent state elections and the polls and ram their bill through Congress using controversial reconciliation rules. The problem: There are as many as 90 House Democrats who are vulnerable in the November elections, and at least half are moderate Democrats who weren’t ever enamored with health care proposals written by their more liberal leadership.

The second is “Plan B,” a scaled-down bill costing about a third of the big bill and far more modest in giving the government authority over the health care system. It could likely attract some Republican votes and give Democrats, particularly moderates, a legitimate claim that they listened to voters and acted in a more measured way. It also would give the president and the Democratic congressional leadership something positive to show at election time.

The Democrats will use the coming weeks to see if they can talk members of their own party into taking the Great Health Care Leap of 2010.

My sense is that they better have a Plan B ready to go.

After watching this debate, as well as the Clinton health care battle 15 years ago, my conclusion is that arrogant partisanship on big, consequential policy issues is a prescription for failure.

What a mess.