MPs called director general Tim Davie's controversial plans to cut BBC local radio "dismayed" and urged him to reconsider.
The service was described as the "jewel in the crown" of the broadcaster and essential in reducing isolation among listeners in a letter from 13 MPs from different parties in the West Midlands.
Since there had been no public consultation, they were "deeply concerned.".
The second day of a 48-hour strike by local radio, TV, and online employees has begun.
The conflict is centered on the BBC's plans to share more programming across its 39 local radio stations.
According to the National Union of Journalists (NUJ), some concessions were made during negotiations mediated by the conciliation service Acas, but they were insufficient.
Following the changes, programming on BBC Radio WM in the West Midlands would be shared with CWR starting at 14:00 BST and then among all Midlands stations in the evenings. Weekends would see an increase in shared performances.
According to the MPs, the action dealt a "serious blow" to local democracy.
"We think that BBC local radio offers a valuable public service of companionship and information in communities, frequently for people who are not well served by other broadcasters. Local radio is listened to by 54 million people each week, according to the letter.
"BBC local radio is a lifeline for news and education, preventing rural isolation, promoting the mental health of rural residents, and serving as one of the jewels in our public broadcaster's crown.
There has been no research presented about the potential effects of these changes, despite the fact that this is license fee money, which almost every household is involved in. ".
The letter, according to NUJ representative Liz Gameson, "showed huge support" for the striking workers.
The West Midlands radio stations of the BBC will all be impacted by the changes.
Due to the majority of journalists and production staff participating in the industrial action, Midlands Today has been off-air during the strike.
The following MPs are among those who signed the letter: Preet Kaur Gill of Birmingham Edgbaston, Matt Western of Warwick and Leamington Spa, Liam Byrne of Birmingham Hodge Hill, Gary Sambrook of Birmingham Northfield, Khalid Mahmood of Birmingham Perry Barr, Colleen Fletcher of Coventry North East, Valerie Vaz of Walsall South, Shabana Mahmood of Birmingham Ladywood, Paulette Hamilton of Birmingham Erdington.
BBC West Midlands has requested a response from the BBC Press Office.
