Sen. John McCain (R-Ariz.) announced he will seek a sixth term in office in 2016, having been first elected to the U.S. Senate in 1986. (Reuters)

Arizona Sen. John McCain (R) announced late Monday night that he will seek a sixth term in the U.S. Senate, acknowledging that he may face a primary challenge from the right but insisting he's up to the task.

"I think I have the knowledge and the background to help this nation through very perilous times, and I believe I can still contribute in many ways to the welfare and benefit of my state," McCain told NBC’s Kelly O’Donnell in an interview released late Monday.

When asked about his age — McCain will be 80 years old on Election Day 2016 and would be 86 by the end of a sixth term — the longtime Arizona senator told O’Donnell that he still keeps a grueling schedule, and isn’t concerned.

"I'm happy to tell you my mother is 103 years old and she's doing well,” McCain said. "Watch me. Take a look at my 18-hour days. Take a look at the hearings we have. Take a look at my legislative accomplishments. Listen, I’m just getting started."

The onetime GOP presidential nominee acknowledged criticisms from members of his own party who have, at times, questioned his conservative bona fides. In 2014, the Arizona Republican Party formally censured him for not being sufficiently conservative — which McCain readily dismissed during his NBC interview with a joke: “I was also censured by Vladimir Putin.”

"I have to convince the voters all over again.... But I will stand on my record. More so, I will stand on what I can do for Arizona and the nation," he said.

The National Republican Senatorial Committee on Tuesday morning threw its support behind McCain, reaffirming its commitment to helping the Arizona senator win another term.

“We are 100 percent behind John McCain’s reelection campaign. No one has fought more for our country than John McCain, and we will do whatever it takes to ensure he keeps serving Arizona families," said NRSC spokeswoman Andrea Bozek.

For its part, the Democratic Senatorial Campaign Committee knocked McCain on his record while ribbing him on his potential primary challenge.

"Since 2010 John McCain has supported plans to gut Medicare & Social Security, repeatedly voted to shut down the government, and been the bitter, angry face of obstruction and partisanship in Washington," said DSCC spokesman Justin Barasky. "If Senator McCain even wins the Arizona GOP nomination, Democrats are committed to finding a great candidate and running a strong campaign against him."

A 2014 year-end filing with the Federal Election Commission shows McCain with a $2 million campaign war chest.