FACTBOX: U.S. Republican candidates and abortion

(Reuters) - Opposition to abortion has been a key plank in the U.S. Republican Party's platform for the past three decades, enabling it to cement the loyalty of religious conservatives, in particular white evangelical Protestants.

The following are some facts about the main Republican candidates' positions and record on abortion.

-- Rudy Giuliani was raised Roman Catholic and has expressed distaste for abortion, but has said he supports a woman's right to an abortion.

His campaign Web site says he favors "reasonable restrictions on abortion such as parental notification with a judicial bypass and a ban on partial birth abortion -- except when the life of the mother is at stake."

He has said adoptions rose 66 percent in New York City while he was mayor while abortions fell 16 percent.

-- Mitt Romney supported abortion rights in the past but says he has been won over by the arguments made by the anti-abortion movement. Romney is a Mormon and his socially conservative church is generally opposed to abortion except for cases such as rape or when a the mother's life is in danger.

-- Fred Thompson says on his campaign Web site that he would use the presidency to "encourage policies that promote a culture of life" -- code for opposing abortion.

While a senator, Thompson voted in 1999 to ban partial-birth abortions and he has been endorsed by the National Right to Life Committee, a leading anti-abortion group.

-- John McCain has a long anti-abortion voting record and supports overturning the U.S. Supreme Court's 1973 Roe v. Wade decision granting women the right to an abortion.