And then he did something none of the 99 other senators were willing to do: He skipped the vote.
Cruz decided since he couldn't stop the Senate from confirming Lynch as the first African American woman to become the nation's top cop, he wouldn't bother sticking around.
The presidential candidate had a flight to catch for campaign events and a fundraiser in Dallas, before heading to this weekend's Republican confab with GOP mega-donor and casino mogul Sheldon Adelson in Nevada.
Cruz did vote earlier Thursday morning in procedural move to block Lynch's nomination from advancing -- "the vote that mattered," his spokeswoman said. But he was overpowered when the Senate overwhelming agreed, 66 to 34, to end the filibuster.
"The Republican majority, if it so chose, could defeat this nomination, but the Republican majority has chosen to go forward and allow Loretta Lynch to be confirmed," Cruz complained in his floor speech.
By the time the Senate voted a couple hours later to confirm Lynch, 56 to 43, Cruz was gone.
In all, 10 Republicans joined all Democrats in confirming President Obama's choice of Lynch to be the nation's top law enforcement officer.
That was twice the number of Republicans who had publicly said they would back Lynch.
Among the unexpected votes of support: Sen. Mitch McConnell (R-Ky.), the majority leader, who was blamed for holding up Lynch's confirmation longer than all but two attorney general nominees in U.S. history.
Also voting yes was Sen. Thad Cochran, the Mississippi Republican, who relied on primarily Democratic African American voters to beat back a tea party primary challenger last year in a highly unusual campaign strategy.
A yes vote also came from Republican Sen. Ron Johnson of Wisconsin, once a tea party favorite who now faces his own tough reelection in 2016.
The two other Republican senators running for president, Sen. Marco Rubio of Florida and Sen. Rand Paul of Kentucky voted against.
Many of the supportive Republicans, including Sen. Rob Portman of Ohio, who is also up for reelection in 2016, voted for Lynch because, as he put it, she "would be an improvement" over retiring Atty. Gen. Eric H. Holder Jr.
Even though the presiding officer in the Senate reminded visitors that no expressions of views are allowed in the galleries, cheers erupted when the final vote tally was read.
Because it was take-your-child-to-work day, several kids watched too.