The Massachusetts Senate will next meet in a formal session on Monday. Senate President Therese Murray, a Democrat, has been tightlipped about the bill's chances.
Sen. Bruce E. Tarr, a Republican from Gloucester, raised the objection. He said he assumes Democratic leaders believe they have the votes to pass the bill but still holds out hope that enough Democrats may be swayed to vote against it.
"I think there is some doubt about the ultimate outcome. Clearly the vote in the House was not a completely partisan vote," he said. "I'm not sure that anyone has an accurate count on who is on the yes side and who is on the no side."
The delay came a day after the Massachusetts House voted 95-58 in favor of the bill, with 42 House Democrats joining all 16 Republicans in opposition.
Supporters, including House Speaker Robert DeLeo, a Democrat, said the change is needed to ensure Massachusetts continues to be represented by two senators until voters can choose a replacement during a Jan. 19 special election.
Patrick, a Democrat and ally of President Barack Obama, also supports the change.
But critics point out that Democrats changed the succession law in 2004 to create a special election and block then-Gov. Mitt Romney, a Republican, from naming a temporary replacement if Sen. John Kerry had won his presidential bid.
To change the law now that there is a Democrat in the governor's office smacks of hypocrisy, they said.
Kennedy, in a letter sent to lawmakers before his death, urged the change in law saying "it is vital for this Commonwealth to have two voices speaking for the needs of its citizens."
Kennedy died of brain cancer last month.
The debate is being followed closely in Washington, where Democrats hope to regain a 60-vote, filibuster-proof margin in the U.S. Senate ahead of any debate on President Obama's health care overhaul.
Massachusetts Sen. John Kerry, Senate Democratic Leader Harry Reid of Nevada and Massachusetts' all-Democratic delegation to the U.S. House also back the change, saying they need all the votes they can to support the health care change.
Obama presidential counselor David Axelrod has contacted Massachusetts officials and the Massachusetts branch of Obama's political arm, Organizing for America, has sent out e-mails advocating for the change.
U.S. Rep. Barney Frank, D-Mass. said Friday that qualms about whether to allow the interim appointment shouldn't be used to help defeat major policy issues like expanding Americans access to health care.
"Public policy questions important to everyone in America shouldn't be decided by a tragedy of death or some other non-electoral factor," Frank said.
The bill initially would have required the appointee be from the same party as the person who created the vacancy, a Democrat in the case of Kennedy's successor.
That requirement was stripped after critics in the House raised constitutional concerns and noted that more than half of voters in Massachusetts aren't enrolled in any party and would be barred from consideration.
Patrick has said he would extract from the appointee a promise not to be a candidate in the special election.
Those said to be under consideration for an interim appointment include former Gov. Michael Dukakis, former Democratic National Committee Chairman Paul Kirk Jr.; former Massachusetts Senate President Robert Travaglini, former Kennedy staff chief Nick Littlefield, Harvard Law School Professor Charles Ogletree and former state Treasurer Shannon O'Brien.
Candidates seeking the Democratic nomination in the special election include Attorney General Martha Coakley, U.S. Rep. Michael Capuano and Boston Celtics co-owner Stephen Pagliuca. State Sen. Scott Brown and Canton Selectman Bob Burr are seeking the Republican nomination.
Party primaries are scheduled for Dec. 8.