(CNN) Orrin Hatch is facing one of the toughest tasks of his 40-year political career: Ushering a massive tax reform bill through a narrowly divided Senate.

Overhauling the tax code is always a tall order, which is one reason Congress hasn't passed legislation of this magnitude since 1986. But as lawmakers return Monday from the Thanksgiving break, Hatch, the 83-year-old Utah Republican who chairs the tax-writing Senate Finance Committee, faces special challenges.

He has few votes to spare with Republicans holding a 52-seat majority in the Senate. Some GOP lawmakers are wavering and Democratic opposition is loud and insistent. There's no clear strategy for Hatch to win over some lawmakers without alienating others. Meanwhile, polling suggests voters are opposed to the GOP tax plans and Hatch's negotiating skills could be undercut by persistent rumors that he will soon retire, with Mitt Romney positioned to succeed him.

But perhaps the biggest challenge facing Hatch is the existential crisis emerging from Republicans anxious that they haven't racked up any legislative accomplishments this year despite the party holding complete control of Washington. That's creating a sense of urgency to pass something -- virtually anything -- that they can show voters going into next year's midterm elections.

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"Failure is not an option when it comes to the Republican Party and cutting taxes," South Carolina GOP Sen. Lindsey Graham told CNN's Dana Bash Sunday on "State of the Union." "To every Republican senator, the fate of the party is in our hands as well as that of the economy."

President Donald Trump plans to drum up support for the tax reform bill with a Tuesday visit to Capitol Hill. Senate leaders hope to pass their $1.5 trillion tax package as early as Thursday. The bill would repeal Obamacare's individual mandate, permanently slash the corporate tax rate and temporarily cut taxes for some individuals. It would have to be reconciled with a House version before Trump could sign it into law.

Hatch's political future

For Hatch, the tax bill is personal as he considers his political future.

"If he decides not to run for re-election, this would be the capstone of the career of a senator who has passed more legislation than any other person in Congress," said Jason Perry, the director of the University of Utah's Hinckley Institute of Politics.

Though Hatch is widely admired in Utah, three-quarters of Utahans said it was time for someone else to serve as Utah's senator in a recent poll by the Hinckley Institute.

"He sees this as being the culmination of all of his efforts, a challenge that will utilize all of his skills and relationships in Washington," Perry said. "He wants this passed, and you see the passion in it. He's not going to let anything get in his way."

That passion, as well as the pressure he faces, was evident during an unusual outburst from Hatch just before the Thanksgiving recess as the Finance committee considered the tax bill. The normally genteel chairman, long-commended for seeking out bipartisan alliances with the likes of Ted Kennedy, upbraided Democratic Sen. Sherrod Brown for claiming the tax bill would only benefit the rich.

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"I really resent anybody saying that I'm just doing this for the rich. Give me a break," Hatch told the Ohio senator, noting he'd "come from poor people."

"We didn't have anything," he went on, "so don't spew that stuff on me. I get a little tired of that crap."

Later on Twitter, Hatch made it clear passing the legislation is personal for him, reminding his followers that he "grew up in a shack with a Meadow Gold Dairy (billboard) sign for a wall." Hatch has said that he and his wife lived in a chicken coop during law school, and he has joked over the years that after growing up in a house without indoor plumbing: "I never pass a bathroom by."

"I worked as a janitor to pay for law school," Hatch tweeted in mid-November after dressing down his Democratic colleagues in committee. "I believe in opportunity because I've lived it. And that's what we're going to deliver with #TaxReform."

(Broadly speaking, if the Senate bill became law, middle-income groups on average would see their after-tax incomes rise. But those increases are mostly modest and often less than that of the wealthiest households. And those increases for the middle class would eventually disappear in part because their tax cuts would expire after 2025, and because the Senate bill would slow inflation adjustments in the tax code.)

In a telephone interview last week, Graham noted that getting tax reform through the Senate was one of the reasons Hatch ran for re-election in 2012. It is also why he brushes off questions about his retirement: "I don't think he wants to say or do anything that would compromise his ability to get this bill done," Graham said.

"Orrin is one of the few people who was here in 1986 and he's always talked about doing something big on taxes," Graham said. "He is one of the few people on the Republican side who can remember the Reagan tax cut. He talks about that being one of his biggest accomplishments. He was a junior member then. Now he's chairman of the committee, so it feels like this is a kind of historic opportunity."

"If he can shepherd the bill through the Senate, and get a compromise with the House, it would be one of the biggest accomplishments of any Republican," Graham said.

Romney's interest

Romney is widely being encouraged to run for Hatch's seat. In discussions with friends and former advisers, he has expressed strong interest in the post if Hatch were to retire. One source familiar with his thinking said Romney is "mentally there" in terms of being willing to run, but waiting for Hatch to decide.

Another former top Romney adviser would only say: "Senator Hatch will announce his decision, which he has not done yet. Mitt Romney has neither opened the door, nor closed it."

Several Romney backers said there is genuine confusion about Hatch's desires, pointing to reports that he recently added new staff and has been raising money for his possible re-election campaign. At the end of the third quarter, Hatch had $4.7 million in cash on hand. He raised $3.4 million between January and the end of September, according to Federal Election Commission reports. The Hatch Election Committee spent about $10.6 million during his last re-election cycle in 2011 and 2012.

In mid-November, Hatch touted the addition of four new staff members to his team that would add muscle to his Washington office. They include foreign policy adviser Jacob Olidort and Peter Carey, an attorney who joined Hatch's Judiciary committee staff to serve as counsel on criminal justice issues.

Romney and Hatch are longtime friends but haven't spoken in several months, according to aides to both men.

In deference to Hatch, more than a half dozen of Romney's former advisers refused to publicly discuss the possibility of a run by the former Republican presidential nominee until the senator announces his plans. Several said they were concerned any comment could be perceived as a suggestion that Hatch should retire.

A hurdle was removed from Romney's path shortly before Thanksgiving when Boyd Matheson, a prominent Utah Republican and former chief of staff to Sen. Mike Lee, said he would not run for the seat.

Hatch has told friends he is genuinely torn about the decision. His spokesman, Matt Whitlock, said Sunday that Hatch is "focused on leading the Senate's efforts to pass historic tax reform, confirming strong judges to courts around the country, and continuing to fight through the gridlock to deliver results for Utah."

Whitlock added: "He has not made a final decision about whether or not to seek reelection, but plans to by the end of the year."

GOP defections

For now, Hatch has to ensure that GOP defections don't sink the tax legislation. If Democrats unite against the bill, he can only lose three Republican votes.

Republican Sen. Susan Collins of Maine has openly expressed concerns about including the individual mandate repeal in the bill, illustrating the difficult balance that Hatch must strike as he tries to appeal to conservatives without losing moderate support.

Sen. Ron Johnson, a Wisconsin Republican, has said he doesn't support the current version of the bill but hopes it can be fixed in a way that he could ultimately back.

Sen. Bob Corker, a Tennessee Republican, has said he can't support legislation that adds to the deficit. And Trump has predicted that Sen. Jeff Flake wouldn't support tax reform, though the Arizona Republican hasn't definitively said he he'd vote.

Chances of passage got a critical boost last week when Alaska Sen. Lisa Murkowski said she would support including the individual mandate repeal in the legislation. But a spokesperson said she hasn't made a final decision on the overall bill.

Though Hatch styled himself as the champion of the little guy during his fiery exchange with Brown, he regularly argues that government spending should be curbed to prevent future generations from being saddled with debt. In a blunt remark to a small group of reporters during the health care talks in May, Hatch said "the public wants every dime they can be given."

"Let's face it, once you get them on the dole, they'll take every dime they can," Hatch said. "We've got to find some way of getting things under control or this country and your future is going to be gone."

Over the years, Hatch has joked about his "racing" mind, his insomnia, and his quest for efficiency -- recounting to reporters about how he would read memos on the stair master or walking to the gym.

Once known for jogging from one meeting to another, Hatch's pace has slowed in recent years. But his relentless desire to succeed is still evident to those around him. Even now when surrounded by a scrum of reporters after stepping off the subway in the Capitol basement, he does not pause to talk -- continuing on his way while taking questions.

The former amateur boxer has shown both his toughness and irritability in several recent hearings. He chided his close colleague, Ron Wyden, the ranking Democrat on the Finance panel, for speaking out of turn -- leading another Sen. Bill Nelson to note that the exchange was not within Hatch's "nature" as "a gentleman."

"Let me be in control of this committee, not you," Hatch had interjected as Wyden tried to ask a committee witness a question. "I'm getting a little tired of being interrupted all the time and you calling on people and so forth," Hatch continued. "I love you personally, but we're going to run this thing like it should be run."

His impatience recalled his thoughts on his legacy during an interview with the Deseret Morning News in 2003: "I don't waste a second," he told his home-state newspaper. "When I go, people will have to say, 'He made every second count.'"

With his party's future weighing on his shoulders, he'll be asked to prove that this week.