President Barack Obama’s fiscal 2011 budget blueprint will land on the Capitol steps Monday morning, but the tough choices it demands are already dividing Democrats.

Several liberal lawmakers said they think Obama’s proposed spending freeze on nonmilitary domestic spending is premature with the economy still on shaky ground and millions still unemployed.

But the move, backed up by Obama with a veto threat during the State of the Union address, has won cheers from the Democrats’ moderate wing, whose members have been battered back home over the past year and are spooked by Republican Scott Brown’s victory in the Massachusetts special Senate election last month.

“This president’s beginning to draw a line in the sand in a way that I think is necessary,— said Sen. Evan Bayh (D-Ind.), who is running for re-election in November. “Regrettably, Congress needs adult supervision. That’s why we have an executive with a veto pen, and I look forward to him using it if necessary.—

Obama’s challenge in getting votes for his budget was made clear during last week’s speech, when his line calling for a spending freeze earned heartier applause from Republicans than from Democrats. And some liberals, such as Rep. Rosa DeLauro (D-Conn.), an appropriator and Pelosi confidante, refused to stand or applaud the idea at all.

“He’s doing exactly what George Bush would have done,— said Judiciary Chairman John Conyers (D-Mich.), who has been highly critical of Obama’s war policies in particular. Conyers said the president cannot count on his support for the spending moratorium.

“If you’re talking about my vote, boy that budget’s in trouble,— he said. “If you’re talking about what everybody else is going to do, I don’t know.—

Rep. Marcy Kaptur (D-Ohio), who is also an appropriator, said she did a double-take when she first heard about the freeze. “I was hoping it was a typo,— she said. Kaptur, who sits on the Appropriations Subcommittee on Defense, said it didn’t make sense to target domestic discretionary spending on its own since it is such a small piece of the overall budget.

Liberals such as Rep. Jim McGovern (D-Mass.) and Congressional Black Caucus Chairwoman Barbara Lee (D-Calif.) said they plan to comb through the budget to make sure programs helping people in need aren’t on the chopping block.

“I don’t understand how a domestic spending freeze accomplishes creating jobs and turning our economy around,— Lee said last week.

McGovern said any savings Obama is trying to achieve would be “pissed away— in Afghanistan, where Obama has ordered another 30,000 troops. McGovern urged more spending on rebuilding America instead.

Speaker Nancy Pelosi (D-Calif.) has said a freeze “may be necessary— but said it should also apply to defense contractors, who she said have been paid hundreds of billions of dollars in cost overruns.

“We do not support an entitlement program for overruns on the part of military contractors,— Pelosi said.

Getting a budget passed is always a challenge for either party, particularly in an election year. Republicans regularly skipped passing a budget resolution during election years before they lost their majorities in 2006, and a dispute over a domestic spending freeze President George W. Bush sought to impose that year resulted in gridlock as a band of moderate Republicans refused to vote for domestic appropriations bills.

The failure to get Congress’ most basic business done was one of the arguments Democrats used to oust Republicans from office that year.

Both parties, meanwhile, have maneuvered this decade through assorted budget gimmicks to elude spending caps, and Democrats worried about cuts to favored programs in the regular bills could be assuaged by off-budget spending in the forthcoming emergency jobs bill, in the Afghanistan war supplemental or by shifting spending to off-budget mandatory programs.

Republicans generally reacted warmly to the proposed freeze but planned to dig through the budget to find whether it was a freeze in name only. But they, like Kaptur, pointed out that the idea covered only a small percentage of overall federal spending and would do little to reduce deficits expected to top $1 trillion a year.

But even if the GOP supports the spending freeze, its Members aren’t likely to support Obama’s budget — viewed as a political document — in the end.

Votes aside, the fiscal 2011 budget process may be idling for a while. Democrats are focused on finishing a health care bill and want to leave open the option of passing it through budget reconciliation rules approved last year. Those rules would allow Senators to bypass a filibuster but expire once the fiscal 2011 budget is passed.

The budget resolution is supposed to be finished by April 15, although Congress routinely misses that date.