It's not just conservatives who publicly doubt President Obama's economic plans. Moderates and even some on the left have begun to speak up and sound off.

Yet there's little bark, and even less bite, from the Blue Dogs -- a group of 53 Democratic House members who claim to be champions of fiscal prudence. Might that be connected to the $741 million of earmarks for the Blue Dogs in the bloated omnibus spending bill?

It's a standard storyline to silence watchdogs by feeding them. In the classic Sherlock Holmes tale Silver Blaze, the most revealing clue was a dog that didn't bark when the crime was committed.

A few individual Blue Dogs have cast votes against parts of the tidal wave of spending. But as a group, they've not blocked the spending spree even when they had the chance to do so. They've gone along with the spending promoted by Obama and House Speaker Nancy Pelosi (D-Calif.).

Two Democratic Senators publicly called for a Presidential veto of the $410 billion "omnibus" spending bill. None of the Blue Dogs did so. Given a chance to vote for a freeze of federal spending -- as an alternative to the bill's 8% increase -- only seven of the 53 Blue Dogs did so. Ultimately, less than a third of the Blue Dogs voted against the bill -- and none raised vociferous objections.

Sen. Evan Bayh (D-Ind.) supported Barack Obama for President and was considered as a possible running mate. Yet he called the omnibus "a sprawling, $410 billion compilation of nine spending measures that lacks the slightest hint of austerity from the federal government." Sen. Russ Feingold (D-Wis.) was less ardent but still pledged to vote no and urged Obama to veto it.

Contrast that with the recent remarks of a leading Blue Dog, Rep. Charlie Melancon (D-La.): "This week alone, President Obama is doing more to address the serious long-term fiscal problems facing our country than former-President Bush and his congressional allies did during his entire eight-year tenure in office. The Blue Dogs will be President Obama's allies in Congress as he moves to re-institute tough budget enforcement mechanisms, such as pay-as-you-go rules, that have the force of law."

What tough measures? Because the $410 billion omnibus bill followed the $787 billion "stimulus" package, the net effect was a combined 80% federal spending increase this year in the agencies covered by both bills.

Four key spending votes this year have been two votes on the stimulus bill, one on the omnibus and one on a spending freeze. Nine Blue Dogs opposed the stimulus on its first vote and six on the second. On the omnibus, 16 of 51 (at the time) Blue Dogs voted no, but then only seven voted for a spending freeze.

The most consistent naysayers to spending have been Rep. Walter Middick (D-Idaho) and Rep. Collin Peterson (D-Minn.), who voted against the higher spending on three of those four votes. Ten others voted against the higher spending on two of the four opportunities -- Reps. Bobby Bright (D-Ala.), Travis Childers (D-Miss.), Jim Cooper (D-Tenn.), Joe Donnelly (D-Ind.), Brad Ellsworth (D-Ind.), Gabrielle Giffords (D-Ariz.), Parker Griffith (D-Ala.), Frank Kratovil (D-Md.), Heath Shuler (D-N.C.) and Gene Taylor (D-Miss.).

Had the group united, their 53 votes could have changed the outcome on each of these occasions, saving taxpayers hundreds of billions of dollars.

Still their own website describes them this way: "The Blue Dogs are dedicated to a core set of beliefs that transcend partisan politics, including a deep commitment to the financial stability and national security of the United States."

The Blue Dogs have a great opportunity to change the free-spending ways of Congress. Those who tune out conservative voices will often pay attention when someone else sounds the same warning.

When moderate senators like Bayh and Feingold decry the spending, it expands the audience of willing listeners, who may then heed even the voices of conservatives.

When TV stock analyst Jim Cramer -- an avowed Democrat and Obama supporter -- says, "Obama has undeniably made things worse" and caused the "greatest wealth destruction ever," more ears perk up.

It changes the political environment when National Journal's centrist Stuart Taylor writes that Obama "may be deepening what looks more and more like a depression" and that his "spending, debt and government control of the economy" may "leave most Americans permanently less prosperous and less free."

The number of attentive listeners expands when the New York Times' Maureen Dowd writes, "Team Obama sounds hollow, chanting that the status quo is not acceptable, even while conceding that the president is accepting the status quo by signing a budget festooned with pork."

The Blue Dogs have a similar opportunity to be important voices in slowing the spending train. Most are not availing themselves of it. But some are cashing in on the pork barrel opportunities. In the omnibus bill, Rep. Marion Berry (D-Ark.) had $156 million in earmarks; Rep. Earl Pomeroy (D-N.D.) had $137 million; Rep. Stephanie Herseth-Sandlin (D-S.D.) had $55 million. Collectively, the Blue Dogs chalked up more than 600 earmarks spending $741 million on pet projects. (Five had zero earmarks -- Bright, Cooper, Griffith, Kratovil, and Minnick. See this chart for key Blue Dog voting and earmark records.)

Both on short-term spending and long-term commitments like entitlements, the Blue Dogs could play an important role if they assert themselves.

While others bark about this Congress' unprecedented spending binge, it doesn't take a Sherlock Holmes to figure out why so many Blue Dogs are silent.

Washington has a long tradition of trading votes for pork-barrel spending, Blue Dogs are probably no more inclined to do so than anyone else in Congress. And no less.

Ernest Istook is recovering from serving 14 years in Congress and is now a distinguished fellow at The Heritage Foundation.