The Social Security program is under attack and needs to be modernized and strengthened, according to a new report from Democrats on the Joint Economic Committee, which recommends policy to Congress.

"Cuts to Social Security are not a credible solution to pay for the $1.9 trillion that Congressional Republicans have recently added to the deficit in passing their tax legislation," Sen. Martin Heinrich of New Mexico, the committee's ranking Democrat, said in a statement to CNBC. "We must ensure that our seniors are able to retire with dignity."

J.P. Freire, a spokesman for the Republicans on the Committee, said he would have a response for CNBC later.

Some Democrats worry that the recent tax cuts will be used by Republicans to make the case that there's a need to reduce other social programs.

The Social Security Administration's budget is already lower. Between 2010 and 2017, its operating budget fell more than 10 percent, according to the Center on Budget and Policy Priorities. Some Republicans are also looking at proposals that would let people borrow from their future Social Security benefits to pay for current expenses.

The report from the Democrats on the Joint Economic Committee, titled "Social Security: A Promise to American Workers and Families," examines what would happen if the program were scrubbed all together.

"Without Social Security, the modern middle class would not be what it is today," the report reads. "Social Security, however, is under attack."

The elderly poverty rate would be four times as high without Social Security, with 15 million more seniors left struggling to make ends meet, it calculates.