WASHINGTON — President Biden reaches the 100-day mark of his administration on Thursday with much to boast about and even more to worry about.

Since taking office, he has presided over a mass vaccination campaign of 230 million doses and counting that has begun to wrestle the deadly pandemic to heel. The $1.9 trillion rescue plan he shepherded through Congress is popular with the public and has begun to boost the weak economy. And in the space of a few months, Biden has issued a slew of executive orders that have undone many of his predecessor’s policies — all while projecting a steady presence after four years of political turbulence.

It all makes for good bragging rights for Biden’s first address Wednesday night to Congress, where he will likely use the speech to tout those accomplishments, as well as push for a sweeping legislative initiative calling for about $1.8 trillion in spending for education and child care.

But that new proposal, like his recent $2 trillion infrastructure bill, faces much steeper odds in Congress — and suggests that the next 100 days for Biden may be far more difficult than the first. Republican leaders are ramping up their opposition to his agenda and highlighting his biggest failing so far: an inability to handle a large increase in migrant children and teens at the US-Mexico border. And Democrats’ razor-thin majority in Congress may clip the wings of the progressive vision he offers on Wednesday.

”We see his vision. He’s laying it out for us,” said Douglas Brinkley, a presidential historian at Rice University. “What we’re not seeing is how it’s going to get funded and whether he can sell the American people on it.”

The end of a president’s first 100 days has formed a traditional, although somewhat arbitrary, demarcation point since Franklin Delano Roosevelt referred to the period after a flurry of activity at the start of his administration to address the Great Depression.

Biden appears well aware of the benchmark and determined to secure his place in history. He met with a group of historians at the White House last month and has referenced learning from past presidencies in deciding what initiatives to push. He also decorated the Oval Office with a large portrait of Roosevelt, who transformed the country through sweeping social welfare programs.

“Successful presidents — better than me — have been successful, in large part, because they know how to time what they’re doing: order it, decide and prioritize what needs to be done,” Biden said last month.

Biden has done that well over his first 100 days, highlighted by his work on the pandemic, Brinkley said.

“He’s brought a sense of confidence, calm, and control across the country,” Brinkley said.

Democrats such as Representative Katherine Clark of Melrose, the assistant House speaker, declare the start of Biden’s term a success — and just the beginning.

“I think the first 100 days have been both hopeful and healing,” she said. “He’s fulfilling what he promised, and more important, he’s meeting this moment of great challenge for American families.”

Of the 61 actions Biden promised to take in his first 100 days, he has fulfilled 25 of them, according to a review this week by the Associated Press. All but three of those unfulfilled promises, including ending prolonged migrant detention, increasing the corporate tax rate, and rejoining the Iran nuclear deal, are in progress.

The $1.9 trillion American Rescue Plan, passed by Congress without any Republican votes, was Biden’s only major legislative victory, but that equals Ronald Reagan’s record in his first 100 days and surpasses the records of several predecessors, according to an analysis by the American Presidency Project at the University of California Santa Barbara.

Nineteen of those orders reversed previous actions, most put in place by Donald Trump, said Terri Bimes, a political scientist at the University of California Berkeley.

“He’s willing to use executive power. He doesn’t flaunt it maybe like Trump did,” said Bimes.

“It’s much harder to reverse legislation, as we’re seeing with the Affordable Care Act,” she said.

But with a 50-50 Senate and a slim majority in the House, legislation is hard to come by. Democrats need Republican support for many of Biden’s priorities. They were able to pass the rescue bill using the budget reconciliation process, which prohibits a Senate filibuster. But there are limits to that procedure, and using it requires nearly all Democrats to be on board.

Progressives so far generally have been pleased with Biden, who ran a more centrist campaign than other Democrats in the primaries. Representative Alexandria Ocasio-Cortez, a Democrat from New York, said during a virtual town hall on Friday that Biden “has definitely exceeded expectations” of progressives.

“I’ll be frank, I think a lot of us expected a much more conservative administration,” she said. But approval like that from the left makes it tougher for Biden to get Republican support.

House minority leader Kevin McCarthy on Sunday called Biden’s first 100 days a “bait and switch” after campaigning on a pledge to restore bipartisanship. And Senate minority leader Mitch McConnell has indicated Biden shouldn’t expect much Republican help with his infrastructure bill, a key part of his Build Back Better initiative, criticizing the legislation for not easing environmental regulations.

The popularity of the COVID aid bill will be hard to replicate if future legislation leans more leftward, said Ron Bonjean, a Republican strategist.

“A particular policy might be popular, but if the overall direction is going away from a voter politically, that’s going to get on their radar screen,” he said. “The American people have very short memories. While they’ve received stimulus checks today, in six months they’ll say, ‘What has the government done for me to improve my life right now?’”

The lack of Republican support in Congress raises the stakes for Wednesday night’s address. Biden and White House officials have said they view bipartisanship as getting support from Republicans outside Washington even if they can’t get it from them in Congress.

Trump was focused on his base and didn’t mind operating with low approval ratings, Brinkley said, but Biden has billed himself as a different president and needs to retain some Republican support in the polls to avoid appearing partisan.

“We’ve seen Biden the grief counselor, the hand-holder, the mourner, and the visionary of what makes America great,” Brinkley said. “We now need to see Biden as salesman for his big programs.”

--- Original story here.