The youngest senator in the upper chamber also has the poorest attendance record for this session of Parliament.

Conservative Senator Patrick Brazeau, 37, was absent for 25 per cent of the 72 sittings between June 2011 and April 2012, the Senate attendance register shows.

By the end of that period, the Quebecer was four days away from being fined.

Senators are allowed to miss up to 21 days in each parliamentary session for religious holidays, family illness or obligations, and funerals and grief.

They can also be away on public business, such as travel or a parliamentary delegation, as long it was unavoidable.

The records for May and June have not been submitted yet.

Brazeau wasn't just missing from the Senate floor. Between June 2011 and April 2012, he also missed 65 per cent of meetings at the aboriginal peoples committee on which he sits.

He was away for 31 per cent of the meetings of the human rights committee, where he is deputy chair.

The senator, appointed in 2008 by Prime Minister Stephen Harper, sent an email response to a request for comment.

"The very simple answer to your question with respect to my attendance or lack thereof is for personal matters," said Brazeau, former national chief of the Congress of Aboriginal Peoples.

He did not elaborate, but later posted a message on Twitter directed to the reporter, Jennifer Ditchburn of The Canadian Press: "while u smile Jen, others suffer. Change the D to a B in your last name and we're even! Don't mean it but needs saying."

Brazeau exchanged more tweets with the reporter and users of the social networking site, before issuing an apology:

"I apologize for my comments. They were done because of my personal circumstance regarding your story," he tweeted.

"I'm a hardworker and take my position seriously but personal issues always comes 1st. Ppl are sometimes in need. Sorry!," he added in a second tweet.

Brazeau was very visible in the media in late March, as he faced Liberal MP Justin Trudeau in a televised charity boxing match. He was favoured to win, but lost the fight in a technical knockout.

NDP MP Charlie Angus said Brazeau is the "latest poster boy" for a democratically challenged institution.

"It's surprising that he shows up at all," said Angus. "He's got a gig for life. There's no accountability, there's no censure, he's going to sit there until he's 75."

The NDP supports abolishing the Senate.

Dallaire, Johnson next most-absent

Other senators who top the absentee list are Liberal Romeo Dallaire and Conservative Janis Johnson. Both senators say they have good reasons for their absences.

Dallaire's records show he is six absentee days away from being fined, having missed 22 per cent of the Senate sittings.

The author and retired army lieutenant-general said he has a lot of public engagements and also spent 3½ weeks in the Democratic Republic of Congo, South Sudan and the Central African Republic continuing his research on child soldiers.

"I took that time, as much as I could over Easter, but it ran over into Senate days," Dallaire said in an interview.

Dallaire missed 17 per cent of meetings on both the national security and defence committee and the subcommittee on veterans affairs. Minutes show Dallaire also wasn't present for two of the five meetings of the special anti-terrorism committee.

Johnson was missing from the Senate floor 19 per cent of the time. She is eight days away from being penalized financially.

Johnson emphasizes that she has had a good attendance record during her 22 years in the Senate. The Winnipeg resident says she is the sole caregiver for a terminally ill aunt. She added that she was ill during the winter and her office failed to note that in the register.

She also notes she is the co-chair of the Canada-United States Inter-parliamentary Group.

"I pride myself in doing my job and I work really hard in the province as well ... I take it very seriously," she said.

Johnson missed two-thirds of the meetings of the energy, environment and natural resources committee. She says was directed to sit on the committee against her wishes, by Senator Marjory LeBreton, the government leader in the Senate.

"What happened is they were in the middle of a report or coming to the end of a report that I had nothing to do with," Johnson said of her appointment to the committee last June.

"I asked the leadership not to put me there, but [LeBreton] said, 'Please just stay there.'"

Johnson's record was better for the foreign affairs committee, but she was still absent 24 per cent of the time.

Many senators got to April with perfect attendance. They included Conservatives Con Di Nino and Jacques Demers and Liberals Jim Munson and Percy Downe.

During the last parliamentary session, Liberal Senator Nick Sibbeston was fined for missing 22 days — one more day than he was entitled to.

Poor attendance was more of an issue a decade ago, when a handful of senators missed a vast number of sittings.

Liberal Andrew Thompson resigned in 1998 after the Ottawa Citizen revealed he only attended about five per cent of sittings over more than a decade.