Ken Salazar, former U.S. ambassador to Mexico, says he was so disillusioned with President Joe Biden's handling of the southern border that he briefly considered launching his own 2024 presidential bid, a disclosure he makes in a forthcoming memoir that doubles as a warning shot to Democrats eyeing 2028.

Salazar, a former interior secretary and Colorado senator, says Biden's team refused for too long to call the migration surge a "crisis" and never installed an interagency border czar, as he repeatedly suggested, leaving the political ground open for President Donald Trump.

The book, "Borderlands: My Fight for an Inclusive America," is set for a July 28 release.

Politico, which obtained an advance copy, reported that Salazar concluded that by July 2024, three weeks after Biden's debate with Trump, that he should enter the race himself.

He drafted a platform and called operatives but never declared he was running for president. Biden withdrew and endorsed then-Vice President Kamala Harris, a handoff Salazar calls a "mistake."

Salazar writes that he pressed Biden and senior White House aides to appoint a border czar to drive interagency response, and that the title was instead informally attached to Harris, who was assigned to address "root causes" of migration in Central America.

He concluded the arrangement "was having no effect on migration flows" and questioned whether Harris had been given real authority or had treated the brief as "political suicide."

He also recounts a 2023 exchange in which then-Homeland Security Secretary Alejandro Mayorkas, facing a House impeachment push, told him: "Ken, I have a lot on my plate already. I'm about to be impeached for all this border stuff. The Republicans have it out for me."

Salazar cheered Biden's June 2024 executive order tightening asylum at the border but called it "too late" to reshape the election.

Salazar is now pitching what he calls a "borderlands platform," urging the U.S., Mexico, and Canada to integrate supply chains, jointly patrol shared borders and expand cultural exchange, a framework he likens to President John F. Kennedy's Alliance for Progress.

He told Politico he has met with Sens. Mark Kelly and Ruben Gallego, both D-Ariz., to pitch the platform and has a meeting scheduled with Illinois Gov. JB Pritzker, another fellow Democrat.

The political backdrop sharpens his proposal.

A Politico/Public First poll released April 18 found half of Americans, including roughly 25% of his 2024 voters, call President Donald Trump's mass deportations "too aggressive," even as Republicans hold a trust edge on immigration.

The online survey of 2,035 U.S. adults was conducted April 11-14 with a sampling error margin of plus or minus 2.17 percentage points; subgroup margins are larger.

Pressed three times on a 2028 run, Salazar demurred but did not rule it out.

"Looking ahead, I want this borderlands platform to be part of that agenda for the future," he said.