"The potential is there for action on a lot of things that have been bottled up," Zelizer said in an interview. "We have a disciplined congressional majority and a president who want mostly the same things on a host of big issues. If you're a conservative, you've been waiting for this for a long time."
The common agenda, discussed at length in the Philadelphia meetings Jan. 25-26, includes proposals to cut taxes and reform the corporate tax code; repeal and replace the Affordable Care Act; tighten immigration rules; construct a wall along the border with Mexico; roll back regulations on business, including rules the Obama administration created to combat climate change; and spend up to $1 trillion on infrastructure projects.
In other words, the biggest and most ambitious legislative agenda in years.
There are some differences between the politics of now and of the Great Society era, of course.
After Johnson's landslide win in 1964, liberal Democrats had big congressional majorities, which allowed them to pass bills over the objections of conservative committee chairmen in their own party and to defeat filibusters in the Senate. And Johnson, master politician, seized the opportunity. Politically, the way was paved by the Civil Rights movement, Zelizer writes in his book.
Despite the president's protestations, Trump lost the popular vote in 2016 and, though he won the Electoral College by a sizable margin, his victory was not as sweeping as Johnson's. Voters added to Republican majorities in the House and Senate, but they are tighter than what Democrats had to work with in 1965.
In addition, Trump has relatively low approval ratings in the early weeks of his presidency, and his executive actions, especially a temporary ban on refugees and on immigration from seven majority-Muslim countries, have spurred protests nationwide.
But Trump polls strong with his base, and grass-roots Republicans are primed to make sure he and the Congress deliver on a conservative agenda, Zelizer said. Trump does need to avoid antagonizing lawmakers with distractions, such as his defense of Russia and false assertions of mass voter fraud.
"He could fumble it by making statements that are so beyond the pale for some congressional Republicans, that it would be too costly to continue to support the president," Zelizer said. Trump also needs to be careful not to step too hard on congressional prerogatives with executive actions, he said.
"My sense is that the Republican Congress and the Trump White House will produce less than they advertise," said Sarah Binder, political science professor at George Washington University. She said one-party control is a powerful factor, but partisan polarization leaves little room for GOP defections, and differences among lawmakers — and with Trump — on goals could bring struggles.
"Think about the divisions in the caucuses," Binder said. "We have deficit hawks and also defense hawks who want to increase military spending. The question is, what happens?"
Already, lawmakers are struggling with the mechanics of repealing and replacing the Affordable Care Act, which reaches deeply into the economy, and are talking about "repairing" the Obama program instead. Trump, who had promised immediate repeal, acknowledged on Fox News this week that it's going to take at least well into next year to make changes.
Other tensions between congressional conservatives and Trump were apparent at the recent Philadelphia retreat, undercutting the one-for-all-all-for-one message.
Trump's a populist who believes in big government on some things. He wants to spend on infrastructure repairs, and construction of the border wall could cost up to $20 billion by some estimates. Many lawmakers are worried about how those costs could be accounted for without blowing up the deficit.
"I generally don't vote for anything that's not offset," said Sen. James Risch, R-Idaho, told reporters. "Everything has to be offset."