Forty-seven House Democrats are threatening to derail the Obama administration’s effort to protect Americans from retirement advisers who put their own interest in earning commissions above their clients’ need for expert advice.

Last week, the lawmakers wrote to Labor Secretary Thomas Perez, who leads the effort, asking for a delay in the rule-making process to allow for more public comment. The request is disingenuous. The Labor Department has already held a long comment period on its proposed rules, including four days of public hearings. The next step is to review the comments and then issue final rules.

The Democrats’ request, if granted, would interrupt this process and very likely make it impossible to finalize the rules before the end of 2016, leaving the next administration to grapple with them anew (if a Democrat wins) or ditch them (if a Republican wins).

Worse, the request could be harmful even if it is denied. After final rules are issued, they will almost surely be challenged in court by opponents in the financial industry, who would most likely cite a refusal to allow more comment as evidence that they were not given enough time to weigh in.

The request is also duplicitous. Most of the signatories had voted earlier against a Republican bill to stop the rule-making, which allowed them to cast themselves as champions of the rules. But asking for a delay could achieve the same obstructionist goal.

The rules, proposed in April, would require financial advisers to act in a client’s best interest when giving advice and selling investments for retirement accounts. That would be a big improvement over current practice, which lets many advisers steer clients into high-priced products and strategies, even when comparable and cheaper alternatives are available. By conservative estimates, clients saving for retirement pay billions of dollars a year in excessive fees and commissions. Under a best-interest standard, those billions would stay in savers’ accounts.

President Obama, who has pledged to veto the Republican bill to block the rules, should also be forthright in disagreeing with House Democrats who now seek to delay it and with any Senate Democrats who go along with them. Democratic leaders in Congress, none of whom signed the letter, should also publicly oppose their colleagues’ effort to subvert the process.

Similarly, the Democratic presidential candidates, all of whom have supported a best-interest standard, should speak up for the Labor Department, the rule-making process and, most of all, the millions of Americans who deserve unbiased advice.