Repealing Obamacare’s individual mandate would cause three to five million people to go without insurance and only save up to $80 billion over the next decade, according to an analysis from financial company Standard & Poor's.

The analysis released Friday is drastically different than one from the Congressional Budget Office, which estimated a repeal would save $338 billion over a decade but would lead to 13 million people going without insurance. The numbers are critical as Senate Republicans included mandate repeal in their tax reform legislation and hope to use the savings to fund some tax cuts.

A major difference between the dueling estimates is the S&P report's impact on Medicaid and the individual market, which includes Obamacare’s exchanges and is used by people who don’t have insurance through a job or the government.

“Our estimates are lower because we believe that it is not the mandate penalty, but the intrinsic financial incentives available to most eligible enrollees that drive enrollment in these two markets," said credit analyst Deep Banerjee.

S&P said the vast majority of Medicaid enrollees don’t pay any premium or a cost-sharing requirement. Another 60 percent of enrollees on the individual market receive a subsidy to help pay for insurance.

“As for the nonsubsidized enrollees in the individual market, although some may be enrolling because of the mandate, the majority today are signing up because they need insurance,” S&P said.

Increases in premiums and high cost-sharing requirements such as deductibles are unattractive for those who don’t get a subsidy or don’t need medical care, it added.

While S&P says there would be some drop-offs in the individual market, repealing the mandate would “not stop the majority of this population from re-enrolling. This is also why we expect limited savings from the federal government from the mandate repeal."

Republicans are banking on adding $338 billion in new revenue to help boost the child care tax credit and help pay for middle-class tax cuts. However, S&P predicts the mandate repeal would save only $60 to $80 billion over the next decade.

Senate Republicans’ decision to add the repeal to their tax code overhaul may have cost them some support among centrists. Sen. Susan Collins, R-Maine, who in July voted against a “skinny” repeal bill that included mandate repeal, has said she is concerned about adding healthcare to the tax legislation because it creates new complications.

The GOP can afford only two Senate defections from its 52-48 majority. Vice President Mike Pence can break a 50-50 tie.