Pfizer (PFE) has long been musing about splitting itself up, promising to deliver a decision on the matter by the end of this year. Indeed, it has already spent $600 million to lay the groundwork for a split internally, separating its faster-growing new drugs and its “established” pharmaceuticals into different units. The company is considering whether the two parts could be more valuable as standalone entities than the whole is worth today—if there is “trapped value”—as well as the potential tax benefits of a breakup.

Tax savings have been a primary motivator in Pfizer’s M&A strategy, such as with its proposed mega-merger with Ireland-based Allergan (AGN), which it scrapped in April after the U.S. Treasury issued new rules that negated the benefits. Still, Pfizer CEO Ian Read indicated recently that splitting up the company might allow for at least part of it to pursue a more favorable tax jurisdiction.

But Read apparently is no longer confident that a breakup would be best for Pfizer, or that it would come with the tax advantages he has long sought.

On a quarterly earnings conference call Tuesday, Read also cast doubt on whether breaking up would really release any “trapped value” in the business. Pfizer’s stock price has already been outperforming lately, he explained, and other companies similar to the ones Pfizer is considering breaking off are commanding lower market valuations than they used to. “I do believe the trapped value question has become more complicated,” Read said.

Pfizer’s shares have risen 13% this year.

Analysts spent nearly an hour grilling Read on the pros and cons of a split, with Goldman Sachs’ Jami Rubin even pointedly remarking, “Investors are frustrated that it is taking so long to decide.”

But Read admitted that Pfizer might wait for the outcome of the presidential election before making a decision, as Donald Trump and Hillary Clinton’s tax plans are likely to impact the tax savings the company could achieve through various deals.

“Hopefully if we have a new administration, whichever administration is in, there will be a need to look at tax reform, and tax reform has implications for what you want to do and what kind of taxes you want to pay,” Read said. “So it is an influence in our thinking.”

Trump has promised a tax reform plan that would lower businesses’ tax rate to a maximum of 15%, rendering “corporate inversions unnecessary by making America’s tax rate one of the best in the world.” Clinton, meanwhile, singled out Pfizer in outlining ways she would prevent deals like its Allergan merger and other inversions and tax-saving maneuvers, but pledged reform that would make the U.S. a more competitive place for businesses to operate.

But dividing the business would also limit the cash each would have access to as well, limiting their abilities to invest in R&D, pay dividends, or spend in other areas, Read said. “If you’re one company you have more choices,” he said. “Once you split you permanently divide those cash flows and you basically lose flexibility.”

Acknowledging split-up success stories such as the 2013 spin-offs of Pfizer’s animal health business Zoetis (ZTS) and Abbott Laboratories’ (ABT) pharma division AbbVie (ABBV), Read said he didn’t necessarily believe the same would happen with Pfizer’s remaining businesses. While those units might have been neglected and underinvested in as part of their parent companies, Pfizer already has two management teams in place overseeing its current businesses and “both parts are getting significant attention,” he said.

Pfizer said it even compared the market performance of the S&P 500 and the Guggenheim S&P Spin-Off ETF, which tracks companies that have been spun or split off from a parent corporation, but that there was no clear winner over the longer term.

“The real question is what can be done if the divisions were split versus what can be done if they’re inside Pfizer?” Read said. “Is there some material obstacle inside the company in either of these divisions if they remain inside Pfizer?”

The company still plans to decide whether or not to split by the end of this year, but even if the answer is no, Read said it could still decide to do so in the future, as the option doesn’t have “an expiration date.”

Pfizer’s shares closed down more than 2% for the day, even though the company’s second-quarter revenue and earnings handily beat Wall Street’s expectations, thanks to growth in several of its new drugs as well as acquisitions.