WASHINGTON (AP) — By themselves, Democrats can't stop the Republican-run Senate from confirming President Donald Trump's pick for the Supreme Court. But they're determined to make it agonizing for a pair of pivotal GOP senators to back the nominee.

Just a weekend from Trump's big reveal on Monday, Democrats' early strategy is to cast the battle as either protecting the right to abortion and the 2010 health care law, or emasculating both. Citing Trump's views on the issues, they say the latter is exactly what Trump's selection would inevitably do.

The hope, widely viewed as a longshot, is to pressure GOP Sens. Susan Collins of Maine or Alaska's Lisa Murkowski to vote "no." Neither faces re-election this year, but both are centrists who've backed abortion rights and helped block their party's 2017 drive to repeal former President Barack Obama's health care statute.

If either flips, the nominee's fate will be in Democrats' hands. Republicans control the chamber 51-49, but Sen. John McCain's absence as he battles cancer has pared that edge to 50-49, making every GOP vote decisive.

The pressure on Collins and Murkowski is just starting. Demand Justice, a new group helping coordinate liberal opposition to the pick, has started airing ads in Maine and Alaska, part of $5 million it plans to spend nationally during the campaign.

"Why won't she rule out voting for Trump's anti-choice picks?" both spots ask.

A Republican defection would turn the tables and focus attention on three Democrats seeking re-election in states that gave Trump landslides in 2016: Indiana's Joe Donnelly, Joe Manchin of West Virginia and North Dakotan Heidi Heitkamp.

If Republicans have the votes to prevail, some Democrats looking ahead to November's elections for congressional control want to give the three moderates room to stray if they so decide.

"There's a reason we still have the ACA, OK?" Jim Kessler, vice president of Third Way, the centrist Democratic group, said of Obama's Affordable Care Act, which the Senate narrowly blocked Trump from dismantling last year. "And that's because we have these senators."

But the three moderates' decisions about voting would be far more fraught if the nominee's fate is in the balance. They'd face enormous pressure from the party's liberal base and probably Senate Minority Leader Chuck Schumer, D-N.Y.

"Then his job becomes exponentially harder," Patrick Griffin, a former top Democratic White House and Senate aide, said of Schumer. Griffin said at the point, Schumer would likely tell them, "I need you, because the argument would be defeat of the candidate is paramount."

Whatever happens, the fight offers both parties a chance to raise money and galvanize voters. Right now, it seems unlikely that Senate Republicans would sink a Trump nominee, due to the sky-high stakes and the country's hyper-partisan political climate.

Yet that would still confront top Democrats with a tough balancing act, even as Election Day rolls closer. They'd need to satisfy anti-Trump liberal voters demanding a battle royale against his selection while allowing Heitkamp, Manchin and Donnelly latitude to make their own voting decisions.

The brewing fight is already highlighting Democrats' strains.

Winnie Wong, political adviser of Women's March, said her liberal activist group is planning marches, rallies and "massive civil disobedience" and said Schumer should press all Democrats to oppose Trump's nominee. Women's March helped organize a noisy Senate office building protest against Trump immigration policies last week in which nearly 600 women were arrested.

"I want them to hold the line and I don't want them to cave," said Wong.

Republicans are mocking Democratic opposition to a nominee who's not yet been named. "Radical Left Takes The Reins," headlined an email aides to Senate Majority Leader Mitch McConnell, R-Ky., sent reporters.

Aiming their comments at Collins and Murkowski, Demand Justice and other liberal organizations said Thursday that Trump's nominee must explicitly endorse the rights to abortion, contraception and same-sex marriage and voice support for Obama's health care statute.

Collins has said she would not back someone hostile to Roe v. Wade, the 1973 Supreme Court decision that established the right to abortion. The groups said her litmus test was insufficient because past nominees have said they'd honor precedents but ruled otherwise as justices.

Schumer this week called abortion rights and the health care law "the most consequential issues" at stake in the fight. By painting those guidelines in a New York Times column, Schumer offered a roadmap for Donnelly, Manchin and Heitkamp.

Their states' conservative voters would be uncomfortable with a senator voting "no" based on abortion rights. But defending Obama's health care law is popular, especially provisions like its protections for people with pre-existing medical conditions. That could give those endangered Democrats a safer political pathway to opposing the pick.

Liberal organizations are already preparing the battlefield. The anti-Trump group Indivisible is organizing demonstrations around the country next week. Abortion-rights groups are planning a "Day of Action" for August 26, the anniversary of the 1920 adoption of the 19th Amendment giving women the right to vote.

Brian Fallon, Demand Justice's executive director, said the group plans spots next week in Manchin's, Donnelly's and Heitkamp's home states asking them to continue protecting patients with pre-existing conditions by opposing a nominee who'd threaten that.