President Barack Obama could likely face his first veto override of his presidency this week—which will probably also be the last given his pending exit in January 2017.

The Justice Against Sponsors of Terrorism Act, generally referred to as the 9/11 bill, will return to the Senate Wednesday and to the House as early as Thursday for an override vote before lawmakers take another pre-election recess.

It was the rare bipartisan piece of legislation that met a presidential veto last Friday. The bill grants families of 9/11 victims the right to sue Saudi Arabia for any role the monarchy might have played in the 2001 terrorist attacks.

The last president to have only one veto overridden was President George H.W. Bush, who served one term from 1989 through 1993. For Obama’s two immediate predecessors, Congress mustered up the needed two-thirds majority twice to override Bill Clinton’s vetoes and four times to override George W. Bush’s vetoes.

“This demonstrates that members of Congress are looking ahead to their own re-election and are ready to move on and distance themselves from the president,” says Gary Rose of Sacred Heart University.

Obama could become the first president to serve two full terms with just a single veto overridden, according to numbers tracked by the U.S. Senate, although some two-term presidents had zero vetoes overriden.

Vetoes themselves are tied heavily to political circumstances, said Sarah Binder, a political science professor at George Washington University.

“The pattern for vetoes and veto overrides is a pattern less about the president and his leadership ability than it is tied to the congressional partisanship of the time,” Binder told The Daily Signal in a phone interview. “Vetoes are unusual when you have unified party control, which the president had for his first two years, and the Democrats controlled the Senate for the first six years. So, any bills that passed the House, such as a repeal of Obamacare, were stopped in the Senate. Split control makes it less likely the president will cast a veto.”

Up to this point, Obama was the first president since Lyndon B. Johnson to have zero vetoes overridden. Johnson’s predecessor, John F. Kennedy, also had no vetoes overridden.

The first nine U.S. presidents didn’t have a single veto overridden. Vetoes were somewhat less common in in the early days, as Thomas Jefferson issued zero during his two first terms. James Madison issued seven vetoes and James Monroe issued one veto.

Andrew Jackson was the first to regularly veto bills, issuing 12 over his two terms in office from 1829 to 1837, and Congress didn’t overturn any.

Other presidents to have zero vetoes overturned were Warren Harding, who served from 1821 until his death in 1823; William McKinley, elected in 1896 and assassinated during the first year of his second term; Abraham Lincoln, elected in 1865, also murdered in the first year of his second term; and Lincoln’s predecessor James Buchanan, who served a single term. Other one-term presidents, James Polk and Martin Van Buren, also had zero veto overrides.

White House press secretary Josh Earnest said Obama is very sympathetic to the 9/11 families. But, he said such legislation could expose Americans to lawsuits around the world in international courts.

“Carving out exceptions to sovereign immunity puts the United States at greater risk than any other country in the world by virtue of the fact that we are more engaged around the globe than any other country in the world,” Earnest said Tuesday during the White House press briefing. “That’s the concern the president has. … It’s the president’s responsibility to consider the broader impact that this bill, as it’s currently written, would have on our national security and standing around the world and on our diplomats and service members who represent America around the world.”

Sens. John Cornyn, R-Texas, and Charles Schumer, D-N.Y., co-sponsored the legislation. Cornyn said he looked forward to overriding the veto to “send a clear message that we will not tolerate those who finance terrorism in the United States.”

“It’s disappointing the president chose to veto legislation unanimously passed by Congress and overwhelmingly supported by the American people,” Cornyn said in a statement. “Even more disappointing is the president’s refusal to listen to the families of the victims taken from us on Sept. 11, who should have the chance to hold those behind the deadliest terrorist attack in American history accountable.”

The scarce number of veto overrides is less astounding when considering the comparatively few vetoes. Obama, and his predecessor George W. Bush, each cast a dozen vetoes, and both maintained at least one house of Congress for the first six years of their presidency. In contrast, the previous two-term presidents, Clinton and Ronald Reagan, had 37 vetoes and had 78 vetoes respectively. Clinton had a Democratic Congress for his first two years. Reagan, who had a Republican Senate for his first six years, had nine of his vetoes overridden by Congress.

Even the last two single-termers used the veto pen far more often. George H.W. Bush vetoed 44 bills from a Democratic Congress. Jimmy Carter actually vetoed 31 bills in a Congress controlled by his own party, only two of which were overridden.

Further, the successive presidencies of Franklin Roosevelt, Harry Truman, and Dwight Eisenhower produced more than 1,000 vetoes. Roosevelt, elected to four terms and serving the entirety of three, vetoed 635 bills, and Congress overturned nine. Truman vetoed 250 bills and Congress reversed 12. Eisenhower vetoed 181 bills and Congress only vetoed two.

It isn’t entirely surprising that a veto override would come at this juncture in Obama’s term, Binder added.

“Normally, enough Democrats would stick with the president to prevent a two-thirds majority, but in this case, they might not want to be on the unpopular side of a vote,” Binder said. “When the issue is framed as either standing with 9/11 families or standing with the Obama administration, Democratic members will be hard-pressed to stand with the Obama administration.”

Other presidents with just one veto overridden are John Tyler, who served from 1841 to 1845; Rutherford B. Hayes, who served a single term from 1877 to 1881; Chester A. Arthur, who served from 1881 through 1885; Benjamin Harrison, who served a single term from 1889 to 1893; Theodore Roosevelt, who fulfilled one president’s term and won another in his own right serving from 1901 through 1909; William Howard Taft, who served one term from 1909 to 1913; and the first President Bush.

Having just one discarded veto likely doesn’t speak to Obama’s legacy, said Tim Hagle, a political science professor at the University of Iowa.

“The difference under Obama, and it really started under Bush, is we’ve seen minorities in the Senate blocking a lot of legislation,” Hagle told The Daily Signal in a phone interview. “It’s a nice trick to accuse a do-nothing Congress when nothing gets done, but it’s not a great sign of Obama’s leadership.”

In the final weeks of a national election, the veto override comes at an interesting time, said Gary Rose, the chairman of the political science department at Sacred Heart University, noting Obama’s approval rating is higher than it has been in years.

“It’s unusual for a president to have his veto overridden when his approval rating is actually strong, but this demonstrates that members of Congress are looking ahead to their own re-election and are ready to move on and distance themselves from the president,” Rose said in a phone interview.