Liberal MP Mauril Bélanger, who was diagnosed with ALS last year, has died.

Prime Minister Justin Trudeau tweeted about Belanger’s death on Tuesday night.

"Mauril Bélanger has passed away. He was a great friend, tireless MP and brave fighter. The entire Parliamentary family mourns his loss," Trudeau wrote in the tweet.

Mauril Bélanger has passed away. He was a great friend, tireless MP and brave fighter. The entire Parliamentary family mourns his loss. — Justin Trudeau (@JustinTrudeau) August 17, 2016

On Wednesday, Trudeau also released a written statement to CTV News, calling Bélanger a “politician universally respected by parliamentarians of all parties.”

“Mauril served the people of Ottawa-Vanier for over 20 years, and was a tireless advocate of francophone rights, national unity, and a fair and just society for all,” Trudeau wrote.

“Despite being very sick towards the end of his life, Mauril continued to serve Canadians with great dignity, courage, and strength … We are all the poorer for his passing, but Mauril's immense contributions to our country will be honoured and remembered.”

Two decades in Parliament

Bélanger, 61, was elected on Feb. 13, 1995 for the federal riding of Ottawa-Vanier -- a riding he held until his death.

The Ontario resident was appointed the deputy leader of the government and chief government whip during Paul Martin’s brief time as prime minister.

After being re-elected in the 2015 federal election, Bélanger was in contention to be chosen as the Speaker of the House but withdrew his bid after being diagnosed with ALS, or Lou Gehrig's disease, in the fall.

"I wanted to be Speaker in order to devote my parliamentary knowledge and expertise to the service of the House of Commons and its members," Belanger told CTV News in March.

However, he received a special recognition in March when he was named honorary Speaker of the House for a day.

Having lost the ability to speak due to ALS, he used a chalkboard as well as an iPad to communicate with others.

Bélanger rose to national prominence with his push to have the Canadian anthem's wording changed to become gender-neutral.

When he first proposed the bill in 2014, Belanger argued that it was a simple change in the English version only.

"It's something that I have been reflecting on for quite a while because I think it would reflect the evolution of our country and our society over the last century," he told CTV News in Sept. 2014. "I think it's time that we have a national anthem that is more inclusive."

His private member's bill passed a third and final reading in June 2016, after being blocked several times, with an aim of changing the line in the anthem from "in all thy sons command" to "in all of us command."

Defender of Francophone rights

His greatest achievement in his riding may have been helping to save the Montfort Hospital, Ontario's only francophone teaching hospital. In 1997, the provincial government tried to close the hospital to save money. The Montfort and local leaders fought the closure through the Ontario courts, winning twice in a bid to have it recognized as essential to the Franco-Ontarian community.

In June, the hospital recognized Bélanger's work to save it by presenting him one of 22 medals created to mark a March 22, 1997 rally against the closure. Only nine have been presented to people or groups who are "a symbol of determination, tenacity and pride," the hospital said in a news release. Bélanger, it said, was "a tireless defender of the rights of Francophone minority communities."

ALS, or Lou Gehrig’s disease, is a neurodegenerative disease that kills nerve cells and leaves muscles paralyzed. As the disease progresses, a patient is often left unable to move any part of the body, unable to eat without a feeding tube, and unable to communicate with anything but the eyes. There is no known cure for the disease.

Outpouring of condolences

On Wednesday, Trudeau and MPs signed a condolence book in the Centre Block rotunda at Parliament Hill.

Colleagues across the political spectrum were quick to pay tribute to Bélanger and his dedication to his role as an MP.

Goodbye to my dear friend, Mauril Bélanger. He served with devotion, stayed true to his beliefs and taught us all about courage and dignity. — Geoff Regan (@geoffregan) August 17, 2016

"Goodbye to my dear friend, Mauril Bélanger. He served with devotion, stayed true to his beliefs and taught us all about courage and dignity," House Speaker Geoff Regan tweeted.

Regan also issued a written statement following Bélanger’s passing.

“Mauril was a respected member of our parliamentary community, and will be greatly missed by his colleagues in the House,” Regan wrote.

“His courage in battling against ALS and his determination to continue working on behalf of his constituents and for all Canadians will be remembered. I extend my condolences to his wife Catherine, his family, and his many friends.”

So terribly sad. @Mauril_Belanger was an incredible MP, advocate, mentor and friend. https://t.co/pWlGDYS5RL — Catherine McKenna (@cathmckenna) August 17, 2016

"So terribly sad. @Mauril_Belanger was an incredible MP, advocate, mentor and friend," tweeted Environment Minister Catherine McKenna, the MP for Ottawa Centre.

Praise for Bélanger came from all sides of the House of Commons.

Mauril was a friend and a great parliamentarian. I will miss him. He was a good man. — Rona Ambrose (@RonaAmbrose) August 17, 2016

Interim Conservative leader Rona Ambrose tweeted, "Mauril was a friend and a great parliamentarian. I will miss him. He was a good man."

Our hearts are with Catherine & his family, friends, and caucus colleagues in this time of sorrow. RIP. https://t.co/iw8Degdkue — Michelle Rempel, MP (@MichelleRempel) August 17, 2016

"Our hearts are with Catherine & his family, friends, and caucus colleagues in this time of sorrow. RIP," Conservative MP Michelle Rempel wrote.

Saddened to learn of the passing of Mauril Bélanger. Very well-liked and respected colleague. Our condolences to his loved ones. — Tom Mulcair (@ThomasMulcair) August 17, 2016

NDP Leader Tom Mulcair also responded to the news on Twitter.

"Saddened to learn of the passing of Mauril Bélanger. Very well-liked and respected colleague. Our condolences to his loved ones."