The Irish Catholic Bishops Conference is seeking legal advice on the proposed abortion legislation.
They have described the bill as "an aggressive attack on religious freedom in our society", because it would impose a duty to provide abortions on Catholic hospitals and those who share their beliefs.
The Bishops are supporting a national vigil of prayer for mothers and their unborn babies, which will take place at Knock shrine this afternoon.
It will be attend by the Catholic Primate of All Ireland, Sean Brady.
Spokesperson for the Catholic Bishops Conference, Father Tim Bartlett, said that the event has been planned for some time.
"The title of it is 'Choose Life - We Cherish Them Both', because that is the position we hold, that the life of a mother is precious and is sacred and should be protected in every way possible, and so is the life of a child," he said.
"We respect and cherish them both, and our current law respects and cherishes them both equally."