Senator John McCain, 81, who has proved a major thorn in Mr Trump’s side, was returning to his home state of Arizona after being treated for a viral infection
Senator McCain will miss vote on Republicans' tax bill
Republican leaders confident of passing a sweeping tax overhaul must contend with one last problem if they are to secure Donald Trump’s first legislative victory before the end of the year: the advancing age of their senators.
Having cajoled their wafer thin majority into line, they need everyone to vote when called upon, after losing a senior figure to illness.
On Sunday it emerged that John McCain, 81, who has proved a major thorn in Mr Trump’s side, was returning to his home state of Arizona after being hospitalised for side effects from chemotherapy for a brain tumour and will miss this week’s vote.
Mr McCain’s office said that the senator will return to Washington in January and will continue to get physical therapy and rehabilitation at the Mayo Clinic.
"He is grateful for the excellent care he continues to receive, and appreciates the outpouring of support from people all over the country," his office said. "He looks forward to returning to Washington in January."
Meanwhile, Thad Cochran, 80, is still recovering from having a non-melanoma lesion removed from his nose last week.
Their struggles are seen in part as a symptom of what is by some measures the oldest Senate ever, with eight octogenarians.
The White House is already making preparations for their absence and the prospect of a tied vote. Mike Pence, the vice president, has delayed a planned trip to Israel in case his casting vote is needed to break the deadlock.
Jeanne Zaino, professor of political science at Iona College, said Mitch McConnell, the Republican leader in the Senate, would have to be wily in timetabling the vote to make sure all his forces were present.
“The Republicans on the Senate side are incredibly old and it can have a tremendous impact when the margin is this thin. If they lose just three people — and not only in terms of support on the bill but hospitalised or in some way unable to participate — that can have a huge impact,” she said.
“They are going to have to be very careful about when they schedule this vote.”
It marks yet another hurdle for an administration that has suffered a string of setbacks as it seeks its first legislative victory. Republicans suffered a humiliating blow when they failed to pass their landmark health care bill, which would have repealed ObamaCare, leaving them without any substantial success in Congress so far.
Failing to pass a massive tax cut while controlling both the Senate and House of Representatives would be deeply embarrassing.
The bill offers the widest ranging overhaul of the tax code in three decades, slashing corporation tax from 35 per cent to 21 per cent in an effort to bring overseas business back in to the country, creating jobs for Americans.
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However, critics warn the cuts will add $1.46 trillion to the national debt over the next decade, lowering taxes on the wealthiest, while a reduction in various tax breaks and credits will mean other tax payers will see fewer — if any — benefits.
"This is happening. Tax reform under Republican control of Washington is happening," Paul Ryan, speaker of the House, told rank-and-file members in a conference call on Friday. "Most critics out there didn't think it could happen … And now we're on the doorstep of something truly historic."
Republicans are desperate to hold the Senate vote before the end of the year, ensuring Doug Jones, the Democrat who won a special election in Alabama last week, will not yet have taken his seat.
That will put the Republican majority at 52-48, rather than 51-49.
Either way, it means every aye counts.
Last week, both Mr McCain and Mr Cochrane missed votes. Initially, officials said they would both be available for the tax vote which is expected on Tuesday or Wednesday.
However, Mr McCain had left Washington for Arizona to spend the holidays with relatives.
His daughter, Meghan, said on Twitter: “My father is doing well and we are all looking forward to spending Christmas together in Arizona.”
Mr Trump told reporters he had spoken to Mr McCain's wife to wish him well.
“But the word is that John will come back if we ever needed his vote. And it’s too bad, he’s going through a very tough time, no question about it, but he will come back if we need his vote," he said.
Republican efforts to get invalids to the floor for votes echo that of Ted Kennedy during the early part of Barack Obama’s presidency. He travelled to Capitol Hill several times to vote on health care matters, push through the president’s economic stimulus and help draft what became the Affordable Care Act during the final year of his life after being diagnosed with the same type of cancer as Mr McCain.
But perhaps the most dramatic Senate scene in history came during the Democrats’ successful effort to break the filibuster on what would become the Civil Rights Act of 1964.
As the clerk read through the list of senators’ names he came to that of Clair Engle, who had been brought to the chamber despite being partially paralysed. Mr Engle was unable to speak and could offer no reply. Instead he cast his vote by pointing to his eye to signify “aye”.
Mr McCain has done this before. In July, days after revealing he had been diagnosed with cancer, he delivered a dramatic coup de grace to Mr Trump’s attempt to repeal ObamaCare by striding on to the Senate floor, turning his thumb down and saying “no”.
The tight majority makes every Republican vote a crucial vote.
That could mean more horse-trading as senators demand amendments to the bill, according to Ms Zaino.
“It’s going to be fascinating to see if they have to make last-minute changes because of Senators who realise how much power they have given the precariousness of this vote, and that could spell real trouble for Republicans down the road,” she said.