Campaigners to retain Ireland’s constitutional ban on abortion held their last major rally in Dublin on Saturday ahead of a referendum on the issue later this month, as a government that favors its removal is forced to shift its focus to a crisis over cancer screening for women.
The rally near Ireland’s legislature appeared to attract thousands of supporters. Opinion polls have consistently pointed to a majority in favor of lifting the 35-year-old ban, although the gap narrowed after the government said it wanted women to have access to abortion for up to 12 weeks of pregnancy, and later under certain limited circumstances.
Also Saturday, the campaign to lift the ban said it had secured the support of 1,000 practicing doctors at an event attended by Health Minister Simon Harris, one of the chief architects of the May 25 referendum.
But with less than two weeks until the vote, he and other senior members of the government have been increasingly dealing with a scandal over a state-run program for detecting cervical cancer that had falsely cleared some women. The resignations of some of the officials involved, as well as fresh revelations of missteps in dealing with the problem, have knocked the abortion referendum off the front pages and the radio news broadcasts that play a major part in Irish political debate.
The campaign to retain the ban suffered a setback when Alphabet Inc.’s Google said Wednesday that it would stop carrying advertisements related to the referendum from May 10. That followed a similar announcement from Facebook Inc. that was limited to advertisements coming from overseas. The social-media giants said they were acting to preserve the “integrity” of the referendum.
Campaigners to retain the ban criticized those moves, saying access to social-media platforms is needed to offset what they see as bias in favor of repeal among Ireland’s established media outlets.
“The yes side doesn’t need Google to campaign,” said Niamh Uí Bhriain of the Save the 8th Amendment group.
The social-media companies decided to act after lawmakers who favor repeal expressed concerns that some advertisements were being placed by unidentified overseas groups, pointing to research by the Transparent Referendum Initiative, a not-for-profit group that has been monitoring online campaigning.
The ban on abortion was added to the constitution through a referendum in 1983 as its eighth amendment. Before that vote, abortion was illegal in Ireland.
—Stu Woo contributed to this article.
Write to Paul Hannon at paul.hannon@wsj.com