As Albertsons Cos. and Rite Aid head to an August vote over their planned merger, the message to investors is simple: size still matters.

The deal, announced in February, would create a new retail giant valued at roughly $24 billion that would combine Albertsons' grocery operations with Rite Aid's pharmacy business. But with Rite Aid, investors are expected to hold a roughly 29 percent stake in the new company, and some have pushed back against the combination. They point to Albertsons' burdensome debt load and recent performance struggles.

Shares of the pharmacy chain have dropped roughly 24 percent since it announced the deal.

To sway investors, the two retailers have embarked on a public relations campaign. Those efforts have centered, in part, on the benefits that scale gives them — even as shopping in the U.S. shifts online and away from stores. The nation's largest retailer, Walmart, has been doubling down on its grocery and e-commerce investments. Competitor CVS Health has announced a $69 billion deal to merge with insurer Aetna.

Increased size gives increased ability to bargain with food and consumer companies as retailers focus on competing on price. It could also give Albertsons and Rite Aid a greater ability to find $375 million in cost savings that would help the two invest in necessary technology for the future, the companies argue. The two would have a particularly large presence on the East and West coasts.

"Scale is big here," Albertsons Chief Operating Officer Jim Donald said in an interview. "Scale is what we can use as we continue to [serve] customers online and [in] brick and mortar."

Albertsons is also pushing back against critiques of its performance. The grocer earlier this week reported adjusted earnings before interest, taxes, depreciation and amortization (EBITDA) of $816 million a 5.7 percent jump over the same quarter last year.

Albertsons was formed by Cerberus and a consortium of investors in 2006. The investment firm later merged Albertsons with the grocer Safeway in 2015. But plans to take Albertsons public were sidelined by market volatility and, later, Amazon's acquisition of Whole Foods that upended the grocery market.

Rite Aid had its own plans blocked. Regulators thwarted its attempts to sell to Walgreens Boots Alliance, whittling a down a sale of its entire 4,600 footprint to just 1,932 stores.

But along with scale, Albertsons has about $12 billion in long-term debt and capitalized leases. The deal also gives Cerberus an opportunity to finally bring Albertsons into the public market after owning the company for more than a decade.

"The proposed transaction is in the best interests of Albertsons and Rite Aid management, but not Rite Aid shareholders," Highfields Capital Management, which owns 4.4 percent of Rite Aid's shares, said in announcing last month that it plans to vote against the deal.

Even with scale and Albertsons' improved performance, the challenges are robust.

Amazon's purchase of Whole Foods and planned acquisition of Pill Pack bring the Seattle giant's might to both the grocery and pharmacy business. Kroger has struck numerous deals and partnerships to augment its e-commerce business and has its own pharmacy business. Walmart's investments in technology and price threaten to undercut any retailer that sits between it and specialty grocer Whole Foods.

"They [Walmart] are in the 800-pound guy in our industry," acknowledged Donald.