Democrats on Wednesday rejected a proposed spending bill deal from Republicans due to concerns over policy riders GOP lawmakers want to attach to the must-pass legislation, leaving congressional leaders with fewer than 10 days to reach an agreement to avert a government shutdown on Dec. 11.

House Minority Leader Nancy Pelosi (D-Calif.) met with approximately 100 Democrats Wednesday morning to discuss the offer, which included several policy provisions that would scale back environmental regulations and make it more difficult for refugees from Syria and Iraq to enter the country. Democrats on the Appropriations Committee are moving forward with a counter offer and expect to return it to Republicans by the end of Wednesday, according to the panel’s ranking member Nita Lowey (D-N.Y.)

“What they sent over wasn’t serious,” Lowey said of the Republican proposal. “If they don’t want to shut down the government they’re going to look at our counter-offer and hopefully we’ll have a final bill before Dec. 11.”

Senate Democrats also rejected the offer, according to a Senate Democratic aide.

House Republicans said Wednesday night that they were still waiting for Democrats to send over a counter offer.

“The ball is in their court,” said Appropriations Committee Chairman Hal Rogers (R-Ky.). “We need to get down to brass tacks so we can solve some 100 issues.”

Democrats have warned for weeks that they would not accept a spending bill that includes “poison pill” policy riders like those that would scale back banking regulations or undermine President Obama’s executive actions on climate change.

Democratic lawmakers and aides said the problematic policy riders in the Republican offer include proposals to:

— Prevent the administration from enforcing Environmental Protection Agency emissions regulations;

— Keep President Obama from making good on his pledge to give $3 billion to the United Nations’ Green Climate Fund;

— Impose a moratorium on allowing Syrian and Iraqi refugees to enter the United States until certain security benchmarks are met;

— Lift campaign finance restrictions on coordination between parties and individual candidate campaigns, a measure being pushed by Senate Majority Leader Mitch McConnell (R-Ky.);

— Give health care providers the right to object to providing certain services that go against their religion, better known as a “conscience clause;”

— Strip family planning funding from organizations like Planned Parenthood;

— Block a Labor Department rule to require retirement investment advisers to work solely in the interest of the clients; and

— Freeze a rule requiring for-profit schools to show that a certain percentage of their students are gainfully employed in a recognized occupation in order to remain eligible for federal student aid.

If any of those provisions appear in the final omnibus, they would be deal breakers, according to Democratic aides.

White House spokesman Joshua Earnest told reporters Wednesday that Republicans are “whistling past the political graveyard of a government shutdown” with an offer laden with policy riders.

“The effort that they’re engaged in now is to lard the bill up with ideological riders,” Earnest said. “None of this is part of how the budget process is supposed to work.”

Republican negotiators are working now to find a list of riders that could be bipartisan enough to remain in the bill.

“If it’s just a Republican rider, strictly Republican, that’s hard to get,” said Appropriations Committee member Tom Cole (R-Okla.). “We need Dem support in the Senate and we obviously need a presidential signature at the end of the day.”

Republicans are also pushing Democrats to negotiate on some of the riders that would roll back environmental and financial regulations. Reducing federal regulations would help increase economic growth and could make the spending increases in the bill more palatable to conservatives.

“The policy riders are hugely important because they generate economic growth,” said Republican Study Committee Chairman Bill Flores (R-Texas). “I can find a way to get comfortable with it but we’re going to need to have a lot of those policy riders.”

One of the riders singled out by Democratic leaders as a poison pill may, however, be difficult to oppose in the final negotiations.

Republicans are pushing to include language to impose a moratorium on allowing Syrian and Iraqi refugees to enter the United States until certain security benchmarks are met, which is based on a recently passed House bill.

The White House and many congressional Democrats oppose the proposal, arguing there already are tough security protections in place for the refugee program and that the United States should be welcoming to people fleeing terrorism and despair in their country. But 47 House Democrats voted in favor of the legislation last month.

On Wednesday, some of those Democrats said it would be difficult to oppose the omnibus simply because it included the refugee language.

“I mean, I’m on record, I voted for it — if that’s the only rider and it’s identical to the bill, it would be hard for me to vote no,” said Rep. Gerry Connolly (D-Va.) “But if anybody had asked me for my opinion, I would have counseled don’t put it in there, why do you want to do that?”

There is potential bipartisan consensus to include an effort to reform the visa waiver program, which leaders in both parties have agreed is in urgent need of reform. Rogers said such a venture was “possible” on Wednesday.

Democrats said they are frustrated that Republican leaders appeared to be working on a deal outside of the talks occurring at the Appropriations Committee level.

House Speaker Paul D. Ryan (R-Wisc.) called Pelosi Tuesday night to discuss the offer, which was negotiated by Senate Appropriations Committee Chairman Thad Cochran (R-Miss.) and Rogers in consultation with GOP leaders, aides said.

“The proposal was an Appropriations Committee offer, constructed by the Appropriations Committee,” said Ryan spokeswoman AshLee Strong. “The speaker supported it, but he’s deferring to Chairman Rogers.”

House Republicans will hold a conference meeting Thursday morning to discuss the omnibus.

Lawmakers will have to work quickly if they hope to pass an agreement before the current spending bill runs out on Dec. 11. To pass legislation before that deadline, negotiators realistically will have to produce a bill by early next week.

Republicans said there is still time to work out the details.

Senate Majority Whip John Cornyn (R-Texas) said the talks are ongoing and he dismissed the Democrats’ rejection of the GOP’s offer as “kabuki.”

“As long as people are talking, that’s reason to be optimistic,” he added.

The talks have been further complicated as leaders try to simultaneously negotiate a deal to revive a package of expired tax breaks for businesses and individuals. Republican tax writers presented Democrats this week with a proposal that would permanently extend several business tax credits as well as those aimed at lower and middle income taxpayers, such as the Child Tax Credit, the Earned Income Tax Credit and a refundable tax credit for students known as the American Opportunity Tax Credit.

“It’s a work in progress at the very highest levels,” said Senate Minority Whip Dick Durbin (D-Ill.) “It is all part of the same negotiation.”

Mike DeBonis Contributed to this report.