Already struggling with finances, the Democratic Party has drafted a plan to have taxpayers help pay about $20 million for next summer’s nominating convention, reversing a change Congress approved just a year ago.

Democratic National Committee Chairwoman Debbie Wasserman Schultz, who is also a congresswoman from Florida, has drafted a bill to restore money that both parties used to receive from the federal government to help defray the costs of running their quadrennial conventions.

The Congressional Budget Office revealed the move in a letter released Friday, which said Ms. Wasserman Schultz’s proposal to tap a presidential campaign fund would likely mean each party could get about $20 million in taxpayer money to help with costs.