Last week, I joined more than 100 aides of the late Sen. John McCain, including former chiefs of staff, senior legislative and campaign workers, and some of the senator's longest-serving staff, to endorse John's friend and colleague, former vice president Joe Biden, for president. We did not do so lightly, but we have no reservations about our decision. We are convinced that Biden's election is in the national interest.

Many of us have been Republicans all our adult lives. Some of us no longer identify as such, but most of us still do. We might have concerns about the recent direction of the Republican Party, and we have varying opinions about how to restore the primacy of the values that attracted us to the party in the first place. But we still believe in those values, and we want them restored to the party of Lincoln and McCain. We do not believe that will happen while Donald Trump is president. And whatever differences of opinion we have, we are united by one urgent purpose: to prevent his reelection.

Working for John was an extraordinary privilege. Each of us cherishes the memory of our association with the inspirational leader who urged us to put country before party and to serve causes greater than our self-interest. The absence of his example and his voice from our public affairs is a tremendous loss for the entire nation, especially in this unusually perilous time in our history.

We try hard to listen for his voice in all important political debates. We can't claim John's endorsement of our decision. But he trusted us to recognize a choice between party and country, and to do what we know is right. We believe electing Biden is not just the right course for the nation but imperative if we are to have any hope of overcoming the grave problems that currently trouble us.

President Donald Trump's inept leadership of the federal government's response to the COVID-19 pandemic has cost many more lives than it should have. His divisive rhetoric and enmity toward those he perceives as adversaries have exacerbated political and social divisions at a time when Americans should be uniting to confront the serious challenges that threaten all of us. His disinterest in American values, his tolerance for despots and his hostility to allies leave us uniquely vulnerable while our adversaries take every advantage of absent American leadership. Last, it has become increasingly clear that Trump's personal qualities — his lack of self-control, his chronic dishonesty, his inattention to his duties and his self-obsession — render him temperamentally unfit for the White House.

Many of us have reservations about some of the views expressed by Biden, by his running mate, Sen. Kamala Harris, and by the Democratic Party's platform. Should the Democratic ticket win the election, we expect to oppose some of the policies their administration pursues. We are, however, encouraged by Biden's long history of seeking bipartisan solutions to serious national problems. We are confident he will fulfill his promise to be a president for all Americans, a confidence we do not have in the incumbent president.

We believe we are acting in accord with John McCain's charge to put "country first" when we urge Americans to elect former vice president Biden and Sen. Harris the next president and vice president of the United States.

Mark Salter served as a staff aide and speechwriter for Sen. John McCain.