Hillary Clinton's running mate was one of two senators who skipped a critical vote on Wednesday to override President Obama's veto of a bill allowing relatives of 9/11 victims to sue the Saudi government.

Despite holding an event 20 minutes away from the Capitol at 9 a.m., Virginia Sen. Tim Kaine was not present when the Senate began voting around noon to override the president's veto.

In a three-page statement accompanying his veto, Obama had said the bipartisan bill, passed by both chambers of Congress earlier this month, "threatens to reduce the effectiveness of our response to indications that a foreign government has taken steps outside our borders to provide support for terrorism, by taking matters out of the hands of national security and foreign policy professionals and placing them in the hands of private litigants and courts."

The Senate voted 97-1 to override the veto with House Minority Leader Harry Reid aligning himself with Obama and casting the sole "no" vote. Vermont Sen. Bernie Sanders, who spent Wednesday campaigning with Clinton in New Hampshire, was the only other senator to skip the vote.

While Kaine has kept silent on both the legislation and Obama's veto, which the House joined the Senate in voting 348-77 to override, Clinton has previously said she supports the congressional effort to "secure the ability of 9/11 families and other victims of terror to hold accountable those responsible."

A spokesman for the Democratic presidential nominee told reporters last Friday that Clinton "would sign this legislation if it came to her desk" as president.

Kaine did not have additional public events listed on his schedule for Wednesday after he joined former Virginia Sen. John Warner, a Republican who recently endorsed Clinton, for a rally in Alexandria, Virginia.

A spokesperson for the Clinton campaign could not be reached for comment, while Donald Trump's campaign called Kaine's absence a "disgrace."

"The failure of Hillary Clinton's running mate Tim Kaine, who was obviouslt afraid to show up to work today and stand with these Americans, is a disgarace," said former New York City Mayor Rudy Giuliani in a statement released by the Republican presidential nominee's campaign.

"It demonstrates his basic inadequacy as a leader," he added of Kaine.