Washington ? Democrats said on Wednesday that Samuel Alito’s confirmation was not guaranteed as senators kept the focus on a 20-year-old document in which the Supreme Court nominee asserted that the Constitution “does not protect a right to an abortion.”

“Anyone who thinks that this nomination is a foregone conclusion is sadly mistaken,” said New York Sen. Charles Schumer, one of several Democrats who used Senate speeches to criticize Alito.

“There are too many questions still to be answered, too many doubts still to be alleviated to say that this nomination is a slam dunk,” Schumer said.

Conservative Republicans came to Alito’s defense, with some committing their votes more than a month before his Jan. 9 confirmation hearing.

Others are warning Democrats not to think about using a filibuster to stop the federal appeals court judge from succeeding retiring Justice Sandra Day O’Connor. She has provided pivotal votes on contentious issues, including abortion, during her 24 years on the high court.

“Even a suggestion that he doesn’t deserve an up-or-down vote is outrageous,” said Sen. Kay Bailey Hutchison, R-Texas.

As conservative and liberal senators bickered, outside advocacy groups planned dueling television advertisements for the Senate’s Thanksgiving break. Groups including the liberal Alliance for Justice plan to announce a television campaign today, while the conservative Committee for Justice plans to respond with a Thanksgiving week ad blitz.

Alito has gotten generally positive reviews from senators since the White House announced his nomination on Halloween as the replacement for Harriet Miers.

Democrats and Republicans have praised Alito’s knowledge, intelligence and his willingness to answer their questions during the private meetings.

But three influential Democrats – Minority Leader Harry Reid, of Nevada; liberal stalwart Edward Kennedy, of Massachusetts; and Schumer, head of the Democratic Senatorial Campaign Committee – said in Senate speeches that they had “significant concerns” about Alito’s nomination.

“A picture of Sam Alito is emerging that may explain why the extreme right-wing is popping champagne corks,” said Reid. Alito, he said, is “one of the most conservative federal judges in the country.”