Opposition home affairs spokesman Jonno Duniam is quitting politics before the end of the year, saying he's "exhausted" and wants to spend more time with his family.

The 43-year-old Tasmanian senator made the shock announcement on Sunday, calling it a difficult decision after 25 years in politics and a decade in the Senate.

"I have given everything to these responsibilities, often at the expense of family," Duniam said in a statement. "It's time I reversed my priorities and I can't do that if I'm to stay in politics."

His departure is a significant blow to the Liberal Party. Duniam was viewed as a rising star and a conservative factional heavyweight. He took on the high-profile home affairs portfolio under Sussan Ley, and under Leader Angus Taylor, his role expanded to include direct control over immigration policy – a key priority as the Coalition tries to fend off the One Nation threat.

Duniam said he told Taylor "some time ago" of his intention to quit. Taylor asked him to stay on for a short period to finish work on immigration policies, including the party's "Australian values migration plan" and restoring integrity to the migration system.

"Now is the right time for my party to choose new Senate team members who will carry forward the fight for Tasmania and for the values in which the Liberal Party believes," Duniam said.

He acknowledged leaving at a "difficult time" for the Coalition but expressed confidence in the leadership of Taylor and Nationals leader Matt Canavan, calling them "outstanding leaders" with an "unrivalled" love for the country.

Home Affairs Minister Tony Burke, his government opposite, paid tribute to Duniam, saying the Liberal Party was losing one of its "best and brightest."

"There'll be plenty of times when Senator Duniam and I are sparring, and he'll say some pretty harsh things, as you'd expect a shadow minister to say, but the reality is, whenever there's been something squarely in the national interest, I've never seen him be anything other than professional," Burke said.

He pointed to the bipartisan ban on hate groups like Hizb ut-Tahrir earlier this year, which Duniam shepherded through Coalition processes. "We're a safer nation because that's been done, and it wouldn't have happened were it not for his leadership as well," Burke said.

Fellow frontbencher Phillip Thompson said he spoke with Duniam on Sunday morning and understood his reasons.

"Missing anniversaries, missing birthdays, missing holidays, you know, being the shadow home affairs minister he's always out and about on TV, travelling, always away from his family, and it takes a toll," Thompson told Sky News.

Thompson called Duniam a "fierce warrior" and a mentor. "He's a great man, great person, and I wish him well."

Duniam played a lead role in the succession planning after Ley stepped down, backing Andrew Hastie who ultimately bowed out of the challenge. Revelations of Duniam's involvement built momentum for the spill.

Duniam was first elected to the Senate in 2016. He leaves federal politics before the next election, which must be held by early 2027.