Sen. Cory Booker (D-NJ) says he’s “still digesting” Speaker Paul Ryan’s Obamacare replacement bill, but he’s already found plenty he disagrees with. There’s the phaseout of the Medicaid expansion that would cut off health care to millions. There’s the cuts to Planned Parenthood, which Booker says would eradicate the sole source of preventative care and birth control for many women.

But then Booker gets to his main objection: "It’s astonishing to me you have a president promising that his health coverage will cover more people with better health care, and there’s no debating that this will cut millions out of health care,” Booker says in an interview in the Russell Senate Office Building late Monday night. “This is bad all around. It’s all kinds of bad.”

On Monday evening, House Republicans unveiled the American Health Care Act — a sprawling Obamacare replacement that aims to overhaul the health care system, primarily by offering tax credits rather than subsidies for purchasing health care.

But Democrats in both chambers of Congress say the bill — which comes into legislative existence already on life-support — is ripe to be picked apart. Four Republican senators are already wavering, saying they may not support the effort if it keeps the Medicaid phaseout.

And in three interviews Monday night, Democratic staffers in both chambers pinpointed four lines of attack on parts of the bill they think are most politically toxic:

1) The American Health Care Act would hurt Medicare

As part of Obamacare, the federal government increased payroll taxes to help pay for the Medicare Trust Fund. That fund is used to reimburse hospitals when seniors come in and need treatment.

Ryan’s bill does away with those new taxes. As a result, the Medicare Trust Fund would go broke about four years earlier than currently projected, in 2025 instead of 2029. This would either force hospitals to either swallow the costs themselves, turn away Medicare enrollees, or both. Here’s what the tax repeal would do to the trust fund, according to the Brookings Institution:

Repealing the ACA's tax on high income households and hospitals would exhaust the Medicare Trust fund by 2024 https://t.co/q1V3MEgZiK pic.twitter.com/CLH83ZT75H — Brookings Econ (@BrookingsEcon) March 6, 2017

Medicare and Social Security are two of the most popular government programs. Democrats believe cutting into it, even indirectly, will infuriate the very people who sent Donald Trump to the White House — the elderly. Seniors groups command a lot of clout on Capitol Hill, particularly with Republicans, and Democrats are optimistic they can be enlisted in the fight against at least this provision.

Democrats believe that if they can turn Ryan’s bill into a referendum on Medicare, it will die. (In 2010, some voters furious over Obamacare memorably demanded “keep your government hands off of my Medicare.”)

“I can tell you that being up here for a while that the groups that mobilize the loudest and the hardest are the senior groups,” one House Democratic aide says. “They’re no joke.”

Added another: “We're going to repeat this over and over: This is a huge threat to seniors.”

The provision is also expected to draw the fierce denunciations of powerful hospital groups on Capitol Hill because it could take away one of their new sources of income. Just a day after the bill was released, stories are emerging across the country noting how badly hospitals stand to be hit under the Medicare Trust Fund reductions.

2) The tax credits are regressive

Like the Affordable Care Act, the American Health Care Act offers tax credits to help people afford coverage on the individual market (for people who don’t get health insurance at work). But compared to Obamacare, the new tax credits — which are largely based on age rather than income — would be more generous to the middle class and wealthy and less generous for the poor.

The average tax credit for Americans earning less than $40,000 per year would go down. But for those making more than $40,000, tax credits would go up under the Ryan plan. (A 60-year-old whose income is around the federal poverty line would see her tax credit cut from around $10,000 to $4,000, while a 27-year-old earning more than $75,000 would get a new $2,000 tax credit.)

The Kaiser Foundation’s Cynthia Cox put this into a chart:

How tax credits would change for #Obamacare enrollees under the just-released House Republican replacement plan #AmericanHealthCareAct pic.twitter.com/t491Lk2ibV — Cynthia Cox (@cynthiaccox) March 7, 2017

Conservatives (in Congress and outside it) were quick to criticize the tax credits for middle-income earners as a “Republican welfare entitlement.”

But the House Democratic staffers I talked to thought Republicans would be bedeviled by what they regard as a blatant hand-out to the rich at the expense of low-income Americans. The effects wouldn’t just be confined to the very poor, either: People making as much as $40,000 could stand to lose thousands of dollars of tax credits, depending on their age and where they live, compared to the benefits they received under Obamacare.

3) The bill defunds Planned Parenthood

Ryan’s bill would also achieve a long-sought goal for many House conservatives: defunding Planned Parenthood by blocking it from receiving Medicaid reimbursement, the organization’s main source of federal funding. (Vox’s Emily Crockett has the full rundown here.)

Planned Parenthood may not be popular with House conservatives, but it is very popular with the country overall. (A poll by The Washington Post in January found Americans oppose defunding Planned Parenthood by a 62 to 31 margin.)

This bill is a mess. It repeals tanning salon tax, defunds Planned Parenthood, cuts Medicaid, cuts taxes 4 rich, trashes individual market. — Brian Schatz (@brianschatz) March 7, 2017

Democrats are optimistic the controversial Planned Parenthood provision can be used to peel wavering Republicans off the Ryan package. Already, Sen. Brian Schatz (D-HI) and Sen. Patty Murray (D-WA) have released statements attacking Republicans for going after Planned Parenthood. In January, perennial swing-vote Sen. Susan Collins (R-ME) bucked the rest of her caucus and opposed her party’s drive to defund Planned Parenthood. (Collins was not among the four Republican Senators who have already announced their doubts about the bill.)

Added Booker in our interview: “I don’t understand how you say to providers who offer some families their only access to preventative care and birth control — for many families who have limited access — to now start cutting funding for Planned Parenthood and similar organizations.”

4) The Medicaid expansion will eventually be phased out

The American Health Care Act would eventually end the Affordable Care Act’s expansion of Medicaid to many more low-income Americans — and Democrats see that provision as a target.

Ryan’s bill will preserve Obamacare’s Medicaid expansions in the states until 2020, avoiding more immediate cuts that many observers expected. But even with that new delay as a compromise measure, Democrats think moderate Republicans will balk at the plan to eventually roll back spending.

They noted that Medicaid may not be as popular as Medicare, but there’s still widespread bipartisan support for the program. That’s even the case for Republicans, as this CNN poll makes clear.

61% oppose (vs. 37% support) cutting federal funding for Medicaid according to new CNN poll. Even half (46%) of Republicans oppose it. pic.twitter.com/9RyD9PeJvp — Nick Gourevitch (@nickgourevitch) March 7, 2017

One House Democratic aide pointed to the list of 15 Republican governors who have recently lobbied for Congress to keep the Medicaid expansion. Republican senators from governors’ states will have to vote for Ryan’s bill if it’s going to pass the Senate.

Gov. Brian Sandoval (R-NV), for instance, has openly criticized the Medicaid rollback. His state’s Sen. Dean Heller (R-NV) is expected to be one of the swing votes on the bill. The same situation faces Sen. Rob Portman (R-OH), Sen. Mike Lee (R-UT), and a handful of other Republican senators.

In other words, these moderate Republican senators would be voting to cut a program that their home-state Republican governors viewed as crucial. And that’s not counting all the other voices, from Planned Parenthood to senior groups, that Democrats think will soon be bringing the heat against congressional Republicans.