WASHINGTON » Two days before joining other presidents in Texas to commemorate the 50th anniversary of the Civil Rights Act, President Barack Obama tackled enduring inequality himself Tuesday, in this case economic disparity based on gender.

His action? Signing a memo seeking statistics on contractor salaries and an executive order barring federal contractors from retaliating against employees who discuss their pay.

If the photo-friendly ceremony in the East Room was not exactly the stuff of Mount Rushmore, it did reflect a broader question about the state of the presidency a half-century after Lyndon B. Johnson enacted monumental change in American society: Is it even possible for a president to do big things anymore?

For better or worse, Johnson represented the high-water mark for U.S. presidents pushing through sweeping legislation not just the Civil Rights Act but the Voting Rights Act, Medicare and major measures on immigration, education, gun control and clean air. No president since has approached that level of legislative success, although there are people who argue that is a good thing because government should not be so intrusive.

But Obama and many Democrats are not among them. At this stage of his presidency, Obama has become a symbol of liberal frustration over his inability to use government to bring about change. Republicans publicly, and some Democrats privately, blame Obama for not doing more to work across the aisle. The White House and many Democrats scoff at that, laying stalemate at the feet of what they call an obstructionist Republican Party.

Certainly, Obama can point to landmark actions from his first term, most notably his health care program, the most significant expansion of the social safety net since the Johnson era. He also pushed through an economic stimulus intended to pull the country back from the abyss and Wall Street regulations intended to avert another crisis. But those actions were accomplished in his first two years, back when he had a Democratic Congress and before sky-high deficits brought on an age of austerity.

Obama now confronts the likelihood that he may not come close to anything like those first 24 months in his final six years in office. Day in and day out, the president with the grand aspirations finds himself signing orders and memos that barely move the needle toward the goals he outlined for himself.

"I’m going to do my small part," he said Tuesday as he signed the executive measures.

Jeffrey A. Engel, director of the Center for Presidential History at Southern Methodist University, said Obama’s health program might ultimately be seen as similar to the lasting legacies of the Great Society or the New Deal.

But the reality of the modern presidency, he said, is that big things are best done right away before second terms devolve into an exercise in aggravation.

"It’s more difficult to achieve massive change after that initial mandate because money and media and constant pinpricks can very effectively take the wind out of any president’s sails very quickly," Engel said.

When domestic prospects recede, presidents often turn to foreign policy, where they have fewer constraints and Congress is a bit player. Obama inherited an empowered national security presidency from George W. Bush and has used it to wage a vigorous drone war and preside over an expansive surveillance program in the pursuit of terrorists.

But he has also had a difficult time dealing with Russia, Syria and the Middle East peace process, and has projected a more restrained U.S. role in the world. If anything, Obama seems intent on being the anti-Johnson by withdrawing troops from Iraq and Afghanistan rather than letting an overseas quagmire like Vietnam come to dominate his presidency and overshadow any domestic accomplishments.

Washington has changed in many ways since the Great Society. Johnson enjoyed such large Democratic majorities that even when his party lost 47 House seats in the 1966 midterm elections, Democrats still held 61 more than Republicans. The country faced crises both parties felt compelled to address. And political deal making then was different with pork projects called earmarks that are now banned seedier, perhaps, but also effective.

Since the Johnson era, the country has grown more skeptical about government. Even Obama’s biggest legislative project, the health care program, was based on helping uninsured Americans buy coverage in the private market, rather than setting up a government-run system like Medicare. But it still stirred widespread opposition.

And the political parties, both ideologically diverse in the 1960s, have grown more homogeneous.

"The nature of politics has changed," said Jennifer Palmieri, the White House communications director. "The electorate is more polarized. I think often members of Congress are more concerned with how the voter on the more enthusiastic side of their party is going to react than they would have 50 years ago. That’s a real change."

Still, few things irritate Obama and his team more than the comparison to Johnson, which they consider facile and unfair. The notion that Obama should exert more energy in cajoling, bargaining and even pressuring lawmakers is a common assessment on both sides of the aisle, but it remains unpersuasive in the Oval Office, despite Johnson’s successes.

"When he lost that historic majority, and the glow of that landslide victory faded, he had the same problems with Congress that most presidents at one point or another have," Obama told The New Yorker last year. "I say that not to suggest that I’m a master wheeler-dealer, but rather to suggest that there are some structural institutional realities to our political system that don’t have much to do with schmoozing."

Not everyone accepts that. Marvin Watson, who was Johnson’s chief of staff, said he made no judgment about Obama or any other president but rejected the notion that Johnson lost sway over time.

"There’s not much difference," he said. "They talk about that because they’re trying to find an excuse why it was done at one time and why it’s not been done since."

Watson agreed that Johnson had a powerful majority but noted that he made a point of negotiating with Republicans anyway.

"We just had a feeling that all positions should be represented," he said.

Mark K. Updegrove, director of the Lyndon B. Johnson Presidential Library and Museum and the organizer of this week’s conference celebrating the Civil Rights Act, said comparisons were hard to make.

"Washington was fundamentally different when LBJ was king of the jungle," he said. "There are many factors there, but one is that I don’t think lawmakers know each other as well as they did in LBJ’s day. One of the ways he was able to get things done is he read the motivations of his colleagues so well. And that was because he knew them so well."

After Obama experienced a year of scant legislative progress he failed to push through even a modest gun control bill in 2013 after the schoolhouse massacre in Newtown, Conn. the president has turned to a strategy of enacting smaller executive actions and using his bully pulpit to persuade states and companies to pick up the cause of, say, raising the minimum wage. And he still has the power to make major changes unilaterally, as he plans to do through environmental regulations of greenhouse gas emissions.

"He would prefer that Congress pick up this legislation and pass it," Palmieri said after Tuesday’s event on pay equity. "It irks him sometimes. But he’s also a pragmatic guy."

She added: "Washington’s not the end-all, be-all. It’s the United States of America, and he’s the leader of it."