House Democrats are pushing to add several health-care provisions to a $1.4 trillion spending bill that must pass by Dec. 20 to avoid a government shutdown, according to congressional aides familiar with the legislation.

U.S. lawmakers are in talks to raise the minimum tobacco age to 21 and repeal Obamacare's so-called "Cadillac tax," an unpopular provision of the health law, as part of the deal that funds discretionary spending across a dozen bills through the rest of the fiscal year, which ends Sept. 30, the aides said.

Lawmakers are also considering eliminating two other Obamacare taxes, providing money for Puerto Rico's Medicaid program and extending certain health programs set to expire to May 22, a senior Democratic aide said, asking not to be identified because the negotiations aren't public.

A senior Republican aide confirmed that the GOP-controlled Senate is considering the measures but cautioned that negotiations were ongoing. Still, the fact that Republicans in the Senate are seriously negotiating the proposals increases the chances that one or more of the provisions could end up in the final bill.

Democrats are pressing to include the CREATES Act, a bill that aims to stop drugmakers from withholding samples of their medicines from generic manufacturers, in the final bill, the Democratic aide said.

Spokespersons for Rep. Nita Lowey and Sen. Richard Shelby, the two top negotiators on the spending deal, did not immediately respond to requests for comment.

Top Democrats and Republicans are rushing to strike a bipartisan deal to fund the government before money runs out Friday. Lawmakers said last week they reached a tentative deal on the overall spending bill, which reportedly includes roughly $1.38 billion in funding for President Donald Trump's wall at the Mexican border.

High health-care costs have become a rare bipartisan issue, drawing support from both Republicans and Democrats in Congress and the Trump administration. Health care remains a top issue for voters ahead of the 2020 presidential election. Congress and the Trump administration are trying to pass legislation before the end of the year that would bring more transparency to health-care costs and, ultimately, lower costs for consumers.

House Speaker Nancy Pelosi and fellow House Democratic leaders had been working for months on a plan to reduce U.S. drug prices before the end of the year. The House last week passed Pelosi's drug-pricing legislation. But the sweeping bill, which would allow the U.S. government to negotiate lower prices for certain drugs, is unlikely to be taken up in the Senate, where Majority Leader Mitch McConnell has previously ruled out any action on it.

The provisions being considered by lawmakers Monday would instead make incremental changes to the health-care landscape that already carry wide bipartisan support.

Obamacare's Cadillac tax, which imposes a 40% tax on the most generous employer-based health insurance coverage, was deeply unpopular with both Republicans and Democrats, who say it punishes the middle class. It was supposed to take effect in 2018, but Congress has delayed the implementation.

The House voted back in July to pass a bill that would scrap the tax, but it wasn't cleared by the Senate.

U.S. lawmakers have also been pushing to raise the minimum age to buy tobacco products to 21 as public health officials attempt to combat a teen vaping epidemic.

The tobacco provision being negotiated as part of the spending deal is modeled after Sen. Brian Schatz's, D-Hawaii, legislation and will include an age restriction on vaping products as well, according to another Democratic aide.