Christie Calls October Election for Lautenberg Seat Gov. Chris Christie of New Jersey, in a decision fraught with political implications, announced on Tuesday that he would schedule a special election in October for the Senate seat left vacant by the death of Frank R. Lautenberg. The decision to set the vote for Oct. 16, a Wednesday, was immediately attacked by Democrats in the state, who said the move by Mr. Christie, a Republican, amounted to squandering taxpayer money to protect his own political ambitions. The special election to replace Mr. Lautenberg, a Democrat, will cost almost $12 million to stage, and will come barely three weeks before the regular November ballot. He died on Monday at age 89. Mr. Christie justified the extra expense by saying a special election would give voters the opportunity to more quickly select their own representative to the Senate. "I don't know what the cost is and I quite frankly don't care," he said. I don't think you can put a price tag on what it's worth to have an elected person in the United States Senate. The governor also scheduled primary elections for Aug. 13. The cost also will be nearly $12 million. He repeatedly denied that political calculations were at play. But Republican insiders privately conceded that adding the Senate contest to the Nov. 5 general election, when Mr. Christie is seeking a second term, would risk energizing Democrats, who outnumber Republicans by 700,000 registered voters in New Jersey. Mr. Christie is believed to have been hoping that a landslide re-election victory would help propel him toward a possible run for president in 2016. At a news conference in Trenton on Tuesday, Mr. Christie said he had yet to decide whom to appoint to fill the seat between now and the special election. He said that his choice would most likely be a Republican and that a decision would come by next week. "I do have a list in my head," Mr. Christie said. You all know me. I don't dawdle. Democrats said they planned to challenge the governor's plan in court. "It's unconscionable that he would put his political interests ahead of the interests of the people," said Assemblyman Joe Cryan, a former state Democratic chairman. And David Turner, a campaign spokesman for State Senator Barbara Buono, the governor's Democratic challenger, called it a "cynical and arrogant decision" that would "needlessly disenfranchise voters" by asking them to go to the polls twice in a short period of time. The October election means that a potentially competitive Senate race will not overshadow the race for governor, which will now remain at the top of statewide ballots in November. Republicans in the state are counting on Mr. Christie, whose popularity has soared since Hurricane Sandy, to draw his supporters to the polls, helping the party's candidates for the State Legislature and for many local offices. Conflicting New Jersey statutes on how to fill Senate vacancies left Mr. Christie with at least two other options about when to schedule the election. Republicans nationally were pressing him to opt for an interpretation that would allow him to delay an election until November 2014. That would have allowed Mr. Christie's choice of an interim senator to give Republicans in the United States Senate the gift of an extra vote, complicating efforts by the White House and Congressional Democrats to advance their agenda, including overhauling immigration laws and pushing through presidential nominations. It would also let a Republican enjoy a year and a half of incumbency in a state where a Republican has not won a Senate election in 41 years. Democrats, meanwhile, were pressing Mr. Christie to add the Senate contest to the state ballot this November. In Washington, Senate leaders reacted in measured terms to Mr. Christie's announcement. Senator Mitch McConnell of Kentucky, the Republican leader, said he did not wish to second-guess Mr. Christie. "I'm sure the governor exercised whatever options he had in the best interest of his state," Mr. McConnell said. And I won't question the path that he's chosen. The top Democrat, Harry Reid, the Senate majority leader, praised Mr. Christie, saying the governor had served the best interests of New Jersey voters. "I have to say that this," Senator Reid said at an afternoon news conference outside the Senate chamber, "he keeps the people of New Jersey involved in who's going to serve them in the Senate. I think it's the right thing to do. Under the law, had Mr. Christie opted for the November election, the nominees for the Senate seat could have been chosen by the state Democratic and Republican committees, rather than by the voters. But Mr. Christie said he insisted on holding a primary. "The process to fill this United States Senate seat must allow the people to have a voice," he said. I will not permit the insiders and a few party elites to determine who the nominee of the Republican Party and the Democratic Party will be. Likely contenders on the Democratic side are Mayor Cory A. Booker of Newark, who several months ago announced his intention to seek the seat in 2014, and Representative Frank J. Pallone Jr. of Long Branch, who has accumulated a large campaign treasury and has long aspired to higher office. People close to Mr. Pallone said that he had privately indicated that he would jump into the race but did not want to openly discuss politics so soon after Mr. Lautenberg's death. Jeff Carroll, a top adviser to Mr. Pallone, deflected questions about the plans, saying, "We'll be making a decision and announcement about the congressman's plans after the funeral." Among Republicans, possible candidates include Lt. Gov. Kim Guadagno and State Senators Joseph M. Kyrillos Jr. and Thomas H. Kean Jr., who each mounted unsuccessful challenges to the state's other United States senator, Robert Menendez. Possible contenders in the state's Republican Congressional delegation include the conservatives Frank LoBiondo and Chris Smith, and the moderates Rodney P. Frelinghuysen and Leonard J. Lance. In discussing whom he would select as a possible interim senator, Mr. Christie said he made no distinction between so-called caretaker appointees and those who would be candidates for the seat. "I'm going to pick a person I believe to be the best person," he said.