Donald Trump has said he doesn't oppose abortion in cases of rape or incest.
The US president insisted, however, that he is "strongly pro-life".
He was commenting in the wake of a number of Republican states introducing restrictive new abortion laws.
Earlier this week, Alabama officials approved the country's strictest abortion laws - banning terminations in almost all cases, including rape and incest.
Pro-choice campaigners have vowed to challenge the bans and restrictions in court, insisting the new laws are unconstitutional.
However, some of those behind the new laws hope court battles will eventually lead to the Supreme Court - where they ultimately hope conservative-leaning judges will vote to overturn the landmark Roe v Wade legislation.
The 1973 decision guaranteed women's rights to an abortion.
Last night, President Trump directly referenced the Republicans' efforts to appoint judges to US courts.
As most people know, and for those who would like to know, I am strongly Pro-Life, with the three exceptions - Rape, Incest and protecting the Life of the mother - the same position taken by Ronald Reagan. We have come very far in the last two years with 105 wonderful new.....
— Donald J. Trump (@realDonaldTrump) May 19, 2019
He said: "We have come very far in the last two years with 105 wonderful new Federal Judges (many more to come), two great new Supreme Court Justices, the Mexico City Policy, and a whole new & positive attitude about the Right to Life."
However, he warned urged Republicans to stay 'united' on the issue ahead of next year's election.
The US president claimed: "We must stick together and Win for Life in 2020. If we are foolish and do not stay UNITED as one, all of our hard fought gains for Life can, and will, rapidly disappear!"
Abortion is a key issue for many Republicans - with Vice President Mike Pence among the most high-profile pro-life politicians in the US.
The Trump administration has implemented policies such as barring organisations providing abortion referrals from receiving federal family planning funding.
A number of prominent Democratic presidential hopefuls - including Joe Biden, Elizabeth Warren, Kamala Harris, Bernie Sanders and Pete Buttigieg - have strongly condemned the restrictive abortion laws being passed by US states.
Senator Warren was among those pledging action to protect existing rights for women if elected next year.
We should pass new federal laws that protect access to reproductive care from right-wing ideologues in the states and ensure access to birth control and abortion care. Laws that will stand no matter what the Supreme Court does. Here’s what that looks like: https://t.co/iBzvjDBCL4
— Elizabeth Warren (@ewarren) May 17, 2019