WASHINGTON – Democrats on Capitol Hill are already working to block President Trump's potential nominee for the Supreme Court. And it's no surprise the battle lines are forming around an issue that's core to both sides – abortion.

Pro-lifers see an opportunity to overturn Roe v Wade, and abortion supporters are very worried that could happen, so both side are using the issue to fire up their bases.

For conservatives who had Supreme Court vacancies in mind when they voted for President Donald Trump, Justice Anthony Kennedy's retirement is a dream come true.

"Kennedy's retirement is a momentous event for the pro-life movement," says Catherine Glenn Foster, president of Americans United for Life.

Pro-choice Democrats have already began speaking out about opposing a pro-life Trump nominee.

"This is a battle line that has been drawn that literally will put women's lives at risk, that under our minds our civil rights, our human rights," Sen. Kirsten Gillibrand (D-NY) said at a recent protest rally.

Senate Majority Leader Mitch McConnell vows to start the confirmation process as soon as the president announces his pick, to schedule a vote before the midterm elections this fall.

Senate Minority Leader Chuck Schumer is leading Democrats crying foul. They say McConnell should wait until after the elections when a new Senate is elected.

"Because Republicans invoked the nuclear option when they were confirming Justice Gorsuch, they only need a simple majority of 51 votes to confirm whoever the president nominates. So really the Democrats don't really have any cards left," says CBN News Capitol Hill Correspondent Abigail Robertson.

However, with abortion rights hanging in the balance, everyone's watching two Republican women.

"On the Republican side I would watch Senators Murkowski and Collins. They are two pro-choice women, so they might oppose a justice that they feel is pro-life, but keep in mind those two did vote for Justice Neil Gorsuch," says Robertson.

She's also watching Democrat Senators Joe Manchin (D-WV), Joe Donnelly (D-IN) and Heidi Heitkamp (D-ND).

They all voted to confirm Justice Gorsuch and are all seeking reelection in states Trump won in 2016.

Catherine Glenn Foster says while she wants to see Roe fall, the goal should be nominating a judge whose duty is to the Constitution, not precedent.

"The fact that we're having this conversation about a nominee opposing Roe v Wade or favoring Roe v Wade, it shows that we’re having the wrong conversation. It means that the process is becoming political as we’re trying to confirm justices instead of looking to justices who do view their highest calling as being to the US Constitution," she said.