Sen. John McCainJohn Sidney McCainTrump's dangerous Guantánamo fixation will fuel fire for terrorists Tech beefs up lobbying amid Russia scrutiny Ad encourages GOP senator to vote 'no' on tax bill MORE (R-Ariz.) is holding a fundraiser in New York City next month — signaling he might run for a sixth term in the upper chamber.

According to an invitation obtained by The Arizona Republic, McCain says he's hosting the event on Dec. 16 at the St. Regis Hotel in Manhattan “as I consider running for re-election to the US Senate.”

McCain, 77, has not made any formal announcement regarding his 2016 plans and has hinted he could leave Congress.

He won a fifth term in 2010 with 60 percent of the vote after avoiding a tough primary from a conservative challenger.

“I am grateful for the support you have given to me and my efforts through the years,” McCain says in the invitation.

“I work to do what I think is right for not only the people of Arizona but the people of our great nation. There is no doubt that we live in very challenging times and every day we see that elections really do have consequences. I vow to continue to do the right thing, not just for my political party and not just against the other political party, but for our country.”

McCain has suggested in past months that he could run again or retire. Last month, he said he was “very seriously considering” a reelection bid. In September, however, he had hinted at leaving Congress.

“The president and I, he's in his last term, I'm probably in mine, the relationship we have had over the past three years is quite good,” McCain told The Wrap in an interview. “Quite good."

If he decides to pursue another term, McCain would turn 80 during the year of the election. Arizona is a red state (Mitt Romney carried it in the 2012 election), and there's been no talk of a serious challenger to McCain — at least not yet.

McCain has served in Congress for 30 years. He was elected to the House in 1982 and to the Senate in 1986.

McCain, the GOP’s 2008 presidential nominee, has ruled out another run for the White House.