The political world is paying tribute to Sen. John McCain, who died Saturday at the age of 81.

These are the messages of mourning and tribute to the Republican senator.

President Donald Trump saying that his “deepest sympathies and respect” are with them.

My deepest sympathies and respect go out to the family of Senator John McCain. Our hearts and prayers are with you!

— Donald J. Trump (@realDonaldTrump) 26 August 2018

Vice President Mike Pence had also published a statement from him and his wife Kare, honouring his service to the nation.

Karen and I send our deepest condolences to Cindy and the entire McCain family on the passing of Senator John McCain. We honor his lifetime of service to this nation in our military and in public life. His family and friends will be in our prayers. God bless John McCain.

— Vice President Mike Pence (@VP) 26 August 2018

Former President Barack Obama released a statement from him and his wife Michelle, saying that “few of us have been tested the way John once was or required to show the kind of courage that he did.”

Our statement on the passing of Senator John McCain: pic.twitter.com/3GBjNYxoj5

— Barack Obama (@BarackObama) 26 August 2018

Former president George W. Bush wrote in the statement that “some lives are so vivid, it is difficult to imagine them ended. It is hard to think of them still,” noting in his statement that “John McCain was a man of deep conviction and a patriot of the highest order.

“Some lives are so vivid, it is difficult to imagine them ended. Some voices are so vibrant, it is hard to think of them stilled. John McCain was a man of deep conviction and a patriot of the highest order.” […] Full statement by President George W. Bush https://t.co/FQVYWIUyGL pic.twitter.com/W8LCxJXRLi

— George W. Bush Presidential Center (@TheBushCenter) 26 August 2018

Former Vice President Joe Biden praised McCain, saying that his life “is proof that some truths are timeless.” Biden’s son had died in 2015 from the same form of cancer which McCain battled before his death.

John McCain was many things – a proud graduate of the Naval Academy, a Senate colleague, a political opponent.

But, to me, more than anything, John was a friend. He will be missed dearly. pic.twitter.com/AS8YsMLw3d

— Joe Biden (@JoeBiden) 26 August 2018

John McCain, prisoner of war, presidential candidate and one of the most influential American politicians of his generation, has died after suffering from brain cancer.

The six-term senator from Arizona, who was 81, had been absent from Washington since last December but remained outspoken to the end, railing against Donald Trump and urging defence of the post-war liberal democratic order – The Guardian reports.