By Stephen Collinson, CNN

(CNN) -- When House Speaker Paul Ryan slams down the gavel to send a huge Republican tax bill to President Donald Trump on Wednesday, he will fulfill a lifetime's ambition of steering a generational economic reform into law.

"This is a promise made, this is a promise kept," Ryan said Tuesday, after an initial House vote on a measure that he has been working towards since signing on as an aide to his mentor, conservative fiscal guru Jack Kemp, in 1993.

Never mind that Ryan's Democratic critics have castigated him for repudiating a reputation as a policy wonk and years of warnings about the perils of bloating deficits and swelling government debt, by embracing a bill that does exactly that.

Ryan is simply savoring the taste of victory.

"My colleagues, this is a day that I have been looking forward to for a long time," Ryan said on the House floor.

"My minute can last for as long as I want it to last," he said, after being interrupted by a protestor, in an aside that revealed how deeply he was savoring a political win that had looked unlikely through a brutal 2017.

Wednesday will be especially sweet for Ryan, over and above his role in putting the most sweeping tax reform bill since the Reagan years on a fast track to Trump's desk.

Revenge against Obama?

The final vote will also represent one last, and long-delayed victory over a political nemesis, former President Barack Obama, because the bill also repeals the individual mandate, the centerpiece of the Affordable Care Act, the 44th President's signature domestic achievement.

That buried victory will close a circle opened years before, in April 2011, when Ryan was humiliated by an Obama attack during a speech on the economy at George Washington University.

Obama warned that Ryan's budget plan was based on a "vision of the future that is deeply pessimistic," leaving many Republicans convinced that the then-President was deliberately trying to embarrass his foe. Obama later admitted that the attack was a mistake, and said he hadn't known ahead of time that Ryan would be sitting in the front row.

Dividend for backing Trump

The tax reform win also offers Ryan a long-awaited dividend for the often taxing and painful experience of dealing with another President: Trump.

Throughout the 2016 campaign Ryan, who had forged himself an urbane and clean living image in his 2012 vice presidential run on Republican Mitt Romney's ticket against Obama, was forced to respond to Trump's outrageous tweets and comments.

Ryan often declined to defend Trump but also risked tainting his own image by pointing out that voters did not face a "binary choice" and were choosing between Trump and Hillary Clinton, implying that for all his faults, the Republican would be far better for America than the Democratic presidential nominee.

He also often mentioned the power of presidents to choose Supreme Court justices and stressed the importance of a sending a conservative to the White House -- or as close to that goal as Trump was likely to get. The new tax law, as well as Trump's choice of Supreme Court Justice Neil Gorsuch, who is already carved out a conservative legacy is payback for his continuing political tightrope walk alongside Trump.

Up and down year

When the President signs the tax bill, it will end a year of turmoil for Ryan that started with the highest of hopes with Republicans assuming a monopoly on power in Washington with Trump's inauguration.

Months later, the speaker tasted humiliation, when he was forced to pull an Obamacare repeal bill from the House floor in March. He rebuked his "10-year opposition party" that was accustomed to being against things, and not for things, amid signs his hold on his restive caucus was fraying.

Ryan also endured scorched-earth attacks pro-Trump media figures -- an unusual experience for someone who had been a darling of the conservative grassroots.

A health care repeal bill did eventually pass the House -- but it failed in the Senate, rising huge doubts about the GOP's capacity to wield power in Washington.

Ryan is vowing that the tax bill was just the start for the GOP and that a new era of reform is brewing in 2018 as he eyes social programs that are beloved of Democratic voters.

But with the mid-term elections fast approaching and Trump's popularity weighing down on his party, and hopes rising among Democrats that they could capture the House next year, it's also possible that the tax win will be the zenith of his speakership.

That's one reason why rumors have been swirling for weeks about Ryan's future, amid speculation he could step down at the end of this election cycle.

CNN reported last week that the speaker had been "soul searching" about his future. But on Tuesday, he told Republican colleagues: "I am not going anywhere anytime soon."