When could anyone have expected that being a champion in the battle against cancer would be a political liability?

It will be, if some of Joe Biden’s opponents for the Democratic Party nomination for president have their way.

While vice president, Biden had called for more research into cancer. That campaign intensified after a brain tumor claimed the life of his son, Beau, in 2015.

After he left office, Biden, who sat out the 2016 presidential campaign, intensified his efforts. He gained help from family and friends — and from some with deep pockets who were willing to help fund his effort. His Biden Cancer Initiative has been supported by more than 200 health care companies and independent groups.

For now, the financial aspect of Biden’s work is not known fully. But The Associated Press reviewed what information was available recently and found that more than $400 million was involved in 13 partnerships with Biden’s initiative.

Clearly, there should be some concern about conflicts of interest if Biden becomes president. He has pledged to make stringent efforts to avoid any hint of them if he goes to the White House. And yes, should he win the presidency, there would need to be abundant independent oversight regarding the matter.

But politics these days has adopted a tone of desperation to find mud, no matter how low one must stoop to collect it, to throw at opponents. Thoughtful, reasonable people — both Republican and Democratic — will respect Biden for his campaign against cancer and insist on evidence of improprieties before making criticism of them.

Doing all one can do in an effort to eliminate one of humankind’s most terrible scourges is not a disqualification for running for president.