Donald Trump denied requests by political aides to submit himself to a forensic evaluation, a choice that partially led to his campaign being unprepared to handle accusations that he mistreated women, according to a Bloomberg report.

NBC News confirmed in May that Trump refused a full vetting early on. A spokeswoman for Trump's campaign did not immediately respond for CNBC's request for comment on the Bloomberg report, which cited people familiar with the matter.

Trump's last two campaign managers — Corey Lewandowski and Paul Manafort — asked to search the Republican nominee's past, which could have helped the campaign with self-opposition research, according to Bloomberg's sources, who were granted anonymity to speak freely about the campaign's start-up days.

The sources said the issue became heated among Trump's closest political advisers and long-time employees at the Trump Organization.

Read the full report from Bloomberg here.