Stepping up its pressure campaign against the major studios, the Writers Guild of America has sent letters to prominent institutional shareholders of Time Warner and AT&T warning them of the impact a strike could have on Time Warner earnings and the pending $85.4 billion merger of the media giants.

“A writer’s strike could undermine AT&T’s primary reason for acquiring Time Warner, which is ownership of compelling content,” WGA West director David Young wrote in the letter sent on Thursday that was obtained by Variety. “A strike could also delay any potential shareholder benefits from the acquisition.”

The shareholders letter follows similar warnings sent earlier this week to top media buyers alerting them to the possibility of a strike against the Alliance of Motion Picture and Television Producers hitting on May 2, just in time to complicate programming decisions for the fall season and the summer upfront advertising sales period. The WGA’s current master film and TV contract with the major studios expires May 1. The sides are scheduled to resume negotiations on April 10, while the guild is holding a strike authorization vote among members the following week.

The outreach to key constituencies of AMPTP member companies marks an aggressive expansion of its effort to make the case for why the guild is pressing key compensation proposals in the talks. The guild is asking for raises in minimums and script fees in an effort to offset changes in the nature of TV series production that have hit writers’ earnings, particularly those in mid- and lower-rung positions.

The guild is pushing for parity at long last for the payment structures for those working on shows for cable and SVOD outlets, where fees remain lower than traditional broadcast network TV, a vestige of a fading era for media.

Some industry observers were dismayed on Wednesday when news of the letters to media buyer first surfaced in Variety, as it was viewed as a sign that the guild’s focus is on waging a PR war against the AMPTP rather than reaching a compromise at the negotiating table. The guild has been increasingly vocal in making the case for the need for changes and increases in the compensation structure for writers during the two weeks since the first round of bargaining talks ended on March 23. The WGA rejected the contract offer put on the table that day by the AMPTP as insufficient to address the income strains for working writers as well as the financial shortfall its health care plan is facing in the coming years.

The shareholders letter repeats assertions by Time Warner executives about the robust health of the TV series business thanks to the growth of international demand for content and the new digital syndication market created by SVOD players like Netflix, Amazon and Hulu.

“While Time Warner has enjoyed the success of the television business, writers’ income has declined sharply in the last five years,” Young wrote. “The average pay of writer-producers working in television declined 23% over the last two years alone. The decline is driven by the growth of short order series with 13 or fewer episodes. Writers, who are primarily paid by the number of episodes produced, often work just as many weeks on short order series as they did on traditional 22-episode series but are paid for fewer episodes. Writer-producers are the only employees on a television production who do not receive additional pay for additional time worked.”

The letter asserts that the cost of its proposals to Time Warner would be about $27.4 million during the three-year term of the proposed contract. It also highlights contract language from the merger agreement reached last October in which Time Warner made standard assurances that there was no labor strife on the horizon that could substantially impact its earnings. “A strike of the writers who create the programming that fuels both Time Warner’s film, studio and network segments has the potential to materially affect Time Warner’s earnings,” Young wrote.

The letter also zeroes in on the issue of the debt load that AT&T will carry after the merger is completed, an factor that has been a flagged as risky by some analysts and observers. “A strike that reduces Time Warner revenue and profits could affect the cash flow and the ability to pay dividends,” Young wrote.

The WGA West acknowledged that letters were sent to about 40 institutional shareholders. Ellen Stutzman, research director for the WGA West, said the goal was to insure that investors were aware of the seriousness of the strike threat.

“The reason AT&T is acquiring Time Warner is the content that guild members create,” Stutzman told Variety. “By not making a fair deal, they’re threatening that.

She noted that there is an intangible cost to a work stoppage where creative endeavors are concerned.

“Strikes have short term and long term effects,” she said. “If work stops, you have the risk of someone not creating an asset that you can monetize and profit from for a 10-year or more period. That could be a long-term drag on earnings. It’s important for investors to know that.”

The AMPTP declined to comment. Reps for AT&T and Time Warner did not immediately respond to requests for comment.

Here is the full letter: