Rojelio Bojorquez, 9, foreground; Laura Bojorquez, 11, and their mother Laura Veronica Perez, visit with the elder Laura's parents - Juana Alicia Bojorquez and Manuel de Jesus Perez Lopez - at the fence that separates Nogales, Arizona, and Nogales, Mexico in Nogales, Arizona, United States. (Jahi Chikwendiu/The Washington Post)

Thirteen years ago, President George W. Bush welcomed Vicente Fox of Mexico to Washington to lay the groundwork for an overhaul of U.S. immigration laws — sensing that fellow Republicans were finally ready to go along with a new legalization effort.

The push included a rare address to Congress on Sept. 6, 2001, when Fox declared that immigrants “invariably enrich the cultural life of the land that receives them.”

Five days later, jetliners hijacked by foreign terrorists crashed into the World Trade Center and Pentagon, heightening security fears and scuttling Bush’s immigration plans.

For more than a quarter century, it has never been the right time for immigration reform. And the biggest stumbling block always seems to be concerns, primarily among conservatives, that border controls are not tough enough and must be strengthened further before anything else can be done.

On Wednesday, Obama will travel to Toluca, Mexico, for an economic summit at a time when his own immigration campaign, launched a year ago, has stalled in Congress amid another backlash over the border . White House officials said that Mexican President Enrique Peña Nieto has pledged to do all he can to help, and Obama predicted to Univision that immigration reform will still happen before he leaves office.

But the situation is largely out of Obama’s hands, and the latest impasse has frustrated longtime advocates.

“When you hear someone say the key to immigration reform is to secure the border, it tells me they either don’t understand the issue or they’re just using it as a pretext,” Carlos Gutierrez, Bush’s former commerce secretary, said in an interview last week. “If we secure the border and do not have reform or a new legal system, then the economy is really going to be in trouble.”

It is a debate that has raged since President Ronald Reagan signed the last major overhaul of immigration laws in 1986, a bipartisan achievement hailed as a solution to the crisis of 5 million immigrants living in the country illegally. The Immigration Reform and Control Act put 2.7 million people on the path toward citizenship, marking the largest legalization program in U.S. history.

But in many ways, the law has been deemed a failure — and stands as one of the chief impediments to a new round of reform. The bill denied legal status to more than 2 million others who had recently arrived in the country, and failed to create a guest worker program large enough to handle the surge of workers streaming across the border over the next two decades.

The number of people living in the country illegally rose again quickly, reaching more than 11.7 million last year.

Former senator Alan Simpson, a Wyoming Republican who helped lead the 1986 negotiations, said a proposal to include a national identification system for workers — aimed at preventing employers from hiring illegal immigrants — was eliminated over Democratic civil-liberties concerns.

“That took out the guts,” Simpson said last week in a telephone interview from his home in Cody, Wyo. Asked when he knew there were flaws in the bill, he replied: “The minute it passed.”

Since then, many Republicans have blamed the law for granting “amnesty” for millions without stemming the flow of undocumented immigrants — and they have vowed not to repeat the mistake.

This month, House Speaker John A. Boehner (R-Ohio) cited “widespread doubt” in his caucus over Obama’s willingness to enforce tougher border controls as the chief impediment to a deal.

“The biggest objection I heard is . . . the legalization will happen but the enforcement never will, and we’ll be right back here in 10 years with another 12 million people,” Sen. Marco Rubio (R-Fla.) said recently. Rubio helped craft a Senate-approved immigration plan last spring that included a 13-year path to citizenship, but he has since withdrawn his support.

Democrats view such talk as a canard for Boehner’s inability to control an unruly caucus, and they note that the Obama administration has deported more immigrants than his Republican predecessor.

But conservatives used similar reasoning to reject immigration deals under Bush. In early 2006, after Sens. John McCain (R-Ariz.) and Edward M. Kennedy (D-Mass.) had introduced a bipartisan bill the previous year, Bush saw the momentum he needed to relaunch his push.

“The debate over immigration reform has reached a time of decision,” Bush declared in a prime-time Oval Office address in May of that year.

Bush dispatched Gutierrez and Homeland Security chief Michael Chertoff to Capitol Hill to make the case to Republicans, focusing on the economic and security benefits.

“Part of what I used to say to people is that absolutely people should pay back taxes, pay penalties, acknowledge they did something wrong, but in our system even if you break the law, you do not go to jail forever,” Chertoff said in an interview last week.

The backlash among conservatives was visceral. Lou Dobbs, then with CNN, launched a recurring feature called “Broken Borders,” in which he railed against the economic costs and criminal dangers of illegal immigrants entering the country.

“The environment was so hostile. We didn’t imagine the opposition would get stronger,” Gutierrez recalled. “It actually grew as we got closer to the vote. Letters going to members of Congress were 100 to 1 against.”

In June 2007, the Senate bill fell 14 votes shy of the 60 it needed to survive a filibuster. After leaving office, Bush cited his failure to achieve immigration reform among his greatest disappointments.

Obama and his allies believed this time would be different.

Although he failed to make much progress on immigration in his first term, the president was reelected in 2012 with more than 70 percent support from Latino and Asian American voters. After their loss, Republican leaders signaled they were open to immigration reform as a way to broaden their appeal to the fast-changing electorate.

Obama launched his immigration campaign with a speech in Las Vegas in January 2013, then stepped back amid fears that his direct involvement could scare away Republicans. He left the details to a bipartisan Senate group led by Charles E. Schumer (D-N.Y.) and McCain, along with Rubio and several others.

Their bill, approved by a healthy bipartisan majority last June, mandates 700 miles of new border fencing, doubles the number of Border Patrol agents to 40,000 and employs aerial drones.

But the proposal has languished in the House, whose Judiciary Committee instead approved a controversial provision that would give federal agents more power to arrest illegal immigrants, patterned after state laws in Arizona. Boehner has sent mixed signals on the prospects for legislation, declaring most recently that Republicans were unlikely to pass reforms because they did not trust Obama.

“This is always going to be a hard issue because it’s just an emotional issue,” said Margaret Spellings, Bush’s former education secretary who now runs the George W. Bush Center in Dallas. Although some of Washington’s lead players have changed, she added, the debate remains the same.

“It’s like a Greek tragedy,” Spellings said. “Here we go again.”