WASHINGTON — From the obscure perch of a backbench senator’s office, Katy Talento used to warn against what she saw as the health hazards of birth control pills — cancer, infertility and miscarriage. From his post at a Christian legal advocacy group, Matthew Bowman spent years attacking the requirement that most health insurance plans cover contraception under the Affordable Care Act.

Now on the inside — one at the White House, the other at the Department of Health and Human Services — Ms. Talento and Mr. Bowman have a clear path to prosecute their strong belief that birth control coverage should not be a mandate from Washington. Both are using arguments they honed over years of battle to ensure that a new rule, expected to be issued this month, to roll back the requirement can withstand legal challenge.

For some of the Trump administration officials tasked with reversing President Barack Obama’s legacy, the path forward has been somewhat rocky. Turning an ideological viewpoint into legislative or administrative policy able to pass legal muster can be difficult for Washington newcomers.

But the architects of the Trump contraceptive reversal, Ms. Talento, a White House domestic policy aide, and Mr. Bowman, a top lawyer at the Department of Health and Human Services, have the experience and know-how that others in the administration lack. As a lawyer at the Alliance Defending Freedom, Mr. Bowman assailed the contraceptive coverage mandate on behalf of colleges, universities and nonprofit groups that had religious objections to the rule. Ms. Talento, a former aide to Senator Thom Tillis, Republican of North Carolina, spent years warning about the health risks of certain contraceptives, especially birth control pills.