The campaign manager behind former President Barack Obama's 2012 re-election slammed Sen. Elizabeth Warren, D-Mass., on Monday for releasing her DNA results three weeks before the 2018 midterm elections, potentially hurting Democrats in the process.

"Argue the substance all you want, but why 22 days before a crucial election where we MUST win house and senate to save America, why did @SenWarren have to do her announcement now? Why can’t Dems ever stay focused???" Jim Messina tweeted.

[Related: Boston Globe botches math in big Elizabeth Warren scoop on Native American ancestry]

Warren shared an analysis of her DNA with the Boston Globe on Sunday to counter criticism she illegitimately claimed to be part Cherokee and Delaware Indian based on family folklore without providing proof. The results examining her ancestry reveal she is between 1/64-1/1024 Native American, her heritage stemming back six to 10 generations.

President Trump had nicknamed Warren "Pocahontas" to highlight how she allegedly used minority status in the 1980s and '90s to springboard her legal career. The Boston Globe, however, reported in September that Harvard University did not factor Warren's ethnicity into its decision to hire her in 1993, nor did other law schools when considering her candidacy for four previous positions.

Messina served as Obama's White House deputy chief of staff before leaving the administration after Obama's re-election to lead Organizing for Action, a nonprofit 501(c)4 group established to promote some of Obama's policy objectives. He has since traveled overseas as a consultant.

Democrats are trying to seize power in the House and possibly the Senate through the 2018 midterm races, following two years of operating in a Republican-controlled Washington.