In the midst of the GOP primaries last year, a senior adviser to Mitt Romney told me the strategy the campaign expected President Obama to use this fall: With fewer than 20 percent of Americans believing that the country was headed in the right direction, Obama would have to acknowledge his failures and say to the American people, “I ask permission to start over.” It was the only way Americans would listen to him; he had to ask for a second chance. He might wait as late as a week before the election, but the moment would come — because Obama had no choice.

Well, Election Day is almost here, and the moment never came.

If President Obama loses tomorrow, it will be because of that fundamental strategic error — he ceded the mantle of change to Mitt Romney. Instead of laying out a new agenda for a second term, and explaining how his next four years in office would be different from last four, Obama chose to run a “stay the course” reelection campaign. He even picked a slogan — “Forward” — that told voters he would keep moving in the same direction.

The problem for Obama is that the vast majority of Americans don’t want to keep moving in the same direction. A recent Fox News poll found that only 24 percent of Americans want the country to “mostly stay on the course it’s on,” while 73 percent say “many policies need to change.” Think of what that means: Even a large number of Obama supporters want to change course, though they want Obama to make the change.

But Obama never offered the American people any change. Instead, he set out to destroy Romney. He launched a relentlessly negative campaign, focused entirely tearing Romney down and making him an unacceptable alterative. Obama spent $100 million on negative ads. He attacked Romney as a heartless corporate raider, vulture capitalist and possible felon, a man who cheated on his taxes, killed a woman with cancer, wanted to destroy the auto industry, and sent American jobs to China. The president’s message was: You may not like me, but you are going to hate him.

At first this scorched-earth strategy appeared to be working, as Romney’s negatives rose and he trailed in the polls. Then, 67 million people tuned into the first presidential debate last month and saw Mitt Romney in person for the first time — strong, respectful, reasonable and presidential. In 90 minutes, the impact of $100 million of ads began to evaporate. The Obama strategy collapsed, and the Romney surge began.

Obama tried to regain the momentum by attacking Romney in the subsequent debates — but it only made the president seem small. Millions of heads nodded when Romney turned to Obama in the final debate and said, “Mr. President, attacking me is not a strategy.”

Obama belatedly saw his mistake. In the closing weeks, his campaign put out a hastily prepared booklet that purported to lay out a second-term agenda, but it was little more than repackaged talking points from his first term. Then, last week, his campaign promised to end on a positive note and “tilt toward the affirmative, toward the future,” in the words of Obama adviser David Axelrod. It never happened. Instead, Obama just continued to attack Romney. At an Ohio rally this weekend, Obama hit Romney for “ruling out compromise,” “massaging the facts,” “pledging to rubber-stamp the tea party agenda in Congress” — and he told his followers that “voting is the best revenge.”

In four years, Obama had gone from asking Americans to vote for “hope” to asking them to vote for “revenge.”

His closing argument was deeply revealing: In the final days of the campaign, Obama still tried to motivate his base with red-meat attacks. Romney, by contrast, had a different closing argument — reaching out to Americans who had voted for Obama four years ago but were disappointed with the results. Standing before a sign that read “Change Begins on Day One,” Romney told a cheering Iowa crowd: “President Obama promised change, but he couldn’t deliver it. . . . The same course we’ve been on will not lead to a better destination. . . . The question of this election comes down to this: Do you want four more years like the last four years, or do you want real change?”

Romney had made himself the agent of change, and Obama the agent of the status quo.

Perhaps the president will still eke out a narrow victory tomorrow. Negative campaigning can be effective. But if Obama had followed the strategy Romney expected — acknowledging that the American people’s discontent, admitting to mistakes, and offering a new course for the country — the election might not even be close.

Going into this campaign, Obama enjoyed a deep reservoir of good will. Americans wanted him to succeed, even though they knew he was failing. They might have given him a second chance if he had asked for one. But he never asked.

Marc A. Thiessen, a fellow with the American Enterprise Institute, writes a weekly online column for The Post.