In the 2010 midterm election, there was much talk about the “enthusiasm gap” between Republicans and Democrats, with Republicans saying they were more enthusiastic about voting than Democrats by a massive nineteen point margin. Many pundits assumed the enthusiasm gap would carry over in 2012, with Republicans hell bent on defeating the president while Democrats were still sour about the prospects for hope and change in Washington.

But in this year’s GOP presidential primary, it’s the Republicans who are deflated. GOP turnout has been down in every state that’s voted so far compared to 2008 except for in South Carolina. Last night’s contests represented a particularly bad night for the GOP. In Missouri, 249,000 people voted in the GOP primary last night, compared to 588,000 Republicans in 2008 and 827,000 Democrats. In Minnesota, 48,000 people voted last night, compared to 63,000 Republicans in 2008 and 214,00 Democrats. In Colorado, 65,000 people voted last night, compared to 70,000 Republicans in 2008 and 121,000 Democrats.

Mitt Romney had an especially bad showing last night compared to 2008, reports Ron Brownstein of National Journal.

In 2008, Romney attracted 25,990 votes while winning the Minnesota caucuses. Last night, he won only 8,090 while finishing a distant third (despite the strong support of the state’s former Republican governor Tim Pawlenty).

Four years ago, Romney won 42,218 votes while winning a decisive victory in the Colorado caucus. Last night, he attracted only 22,875 while finishing second.

In Missouri last time around, Romney won 172,329 votes while finishing third (after John McCain and Mike Huckabee). Last night, he attracted only 63,826 while finishing a distant second to Santorum.

Such dismal turnout from the GOP front-runner is a worrying sign for Republicans, especially since they’ve also ceded the enthusiasm gap to Democrats. Reports Politico:

Almost 6 in 10 Democrats, 58 percent, said they are “very excited” to vote later this year, compared to 54 percent of Republicans that said the same, according to a Public Policy Polling survey conducted for Daily Kos.

This is in contrast to where things stood six months ago, when 48 percent of Democrats and 54 percent of Republicans said they were very excited to head to the ballots in the fall.

Independents and other non-Democrats and Republicans were even less thrilled about voting in November—just 40 percent of them said they were very excited to cast their ballots, while 35 percent said they were not at all excited.

In even more troubling signs for the Republican Party, 25 percent of conservatives said they are not at all excited to vote in November, compared with just 16 percent of liberals who expressed the same lack of enthusiasm.

Romney will still almost certainly become the GOP nominee. But he’s looking like a weaker and weaker candidate by the day.

Ari Berman’s book, Herding Donkeys: The Fight to Rebuild the Democratic Party and Reshape American Politics, is now out in paperback, with a new afterword on the 2012 elections.