Less than three weeks into his administration and despite high approval ratings, President Barack Obama’s signature legislation to revive the U.S. economy is taking hits in the Senate, particularly from fellow Democrats who are decidedly unsatisfied with the bill passed by the House last week.

Although it is standard for the Senate to flex its muscle, new presidents are normally granted a bipartisan honeymoon of at least a few months during which their top initiatives are allowed to smoothly sail onto the Oval Office desk.

But in addition to Republican recalcitrance, a significant number of Senate Democrats are concerned with the size and scope of the $900 billion stimulus bill and have moved unapologetically to rewrite large portions of it.

“Senators get election certificates. We’re sent here to make independent judgments,” Sen. Ron Wyden (D-Ore.) said Wednesday. “But, I will tell you, not just as one, but from a lot of [Democratic] colleagues, we think President Obama is off to a strong, strong start.”

Though Democrats would not be expected to criticize Obama personally, even Senate Republicans have taken pains to praise the president’s motives and effort, particularly his moves to reach out for GOP support. Republican opposition has centered on the contents of the stimulus bill.

And in fact, it’s the House version of the bill that is the root of Obama’s problems, K Street operatives said, adding that the bill contains too many apparent giveaways.

“People are paying attention to what’s in it,” one lobbyist friendly with both sides of the aisle said when asked why there is more than the usual token Democratic opposition. “It’s a bad bill. Why did the [White House] let this get so out of control — it’s the penultimate Christmas tree.”

The American Recovery and Reinvestment Act passed the House last Thursday with little drama and all but 11 Democrats voting for it, albeit no Republican support.

The White House did not signal any major displeasure with the $816 billion measure — the Senate version currently stands at about $900 billion — until it became clear that Senate approval would not be nearly as easy.

Capitol Hill political operatives say it is the severity of the national economic recession that is causing Democratic Senators raise questions about the bill, in part to provide themselves with political cover should the legislation ultimately fail to help jump-start the economy.

This political factor holds even greater resonance for those Democrats who represent conservative-leaning states, of which there are several after two straight election cycles of Democratic Senate pickups.

The negative publicity generated by the bill’s House version has also contributed to many Democrats’ less-than-enthusiastic reaction, in some cases causing more discomfort than the contents of the bill itself.

“The more those stories continue, the more it appears like a boondoggle,” one Democratic Senate aide said.

The aide added that opposing the bill in its current form or offering amendments creates a “cover mechanism for anyone who has concerns.” And it will allow Senators to make changes in the House-Senate conference committee that they can later declare made the bill better.

Senate Democratic leaders, sensitive to the notion that they are in any way slowing down passage of Obama’s inaugural legislative measure, rejected the idea that the chamber has delivered a premature end to the commander in chief’s Capitol Hill honeymoon.

Sen. Max Baucus (D-Mont.) said in an interview Wednesday that his Conference and Obama are on the same page and proceeding at a rate that will allow them to meet the president’s demand that they deliver the bill to his desk by Feb. 16.

Sen. Patty Murray (D-Wash.) sidestepped the question of whether Obama should have received more support for his bill when it arrived in the Senate late last week, given that he is a fellow Democrat and newly inaugurated.

And she noted the unusual speed with which the bill is moving through both chambers of Congress and the extraordinary cooperation between the two branches of government that such movement requires.

“We are just a few weeks into the session here, and we are passing a major economic recovery bill. I think it’s to everybody’s credit that they are working very hard to get this done in a few short weeks, and I expect we’ll get there,” Murray said.

Senate Republicans, seizing on Obama’s outreach to them, have criticized Senate Democrats for, until now, voting down most of their amendments, noting that the president’s civil entreaties are no substitutes for not including their ideas in the stimulus bill.

Still, a failure to include Republican ideas in the stimulus bill is not the driving force in their opposition.

Far more important, GOP aides say, is rising public concern that the bill will not provide any real stimulative effect on the economy, a concern that has provided the Senate GOP with the confidence to begin discussing the possibility of using “procedural” measures to block the bill.

“When they jammed it through the House and told the Republicans to go pound sand, I think that sort of set the tone for this,” Sen. John Thune (R-S.D.) said. “So far, this whole tone of bipartisanship has been, ‘well, we will be nice to you, but we’re not going to include any of your ideas.’

“This is bad policy,” Thune said. “We’ve got to make a stand on this.”