CLARKSBURG — U.S. Sen. Joe Manchin, D-W.Va., who said he had remained undecided on the issue up until the weekend, announced Tuesday he plans to vote against an international accord designed to limit Iran's access to nuclear weapons.

In a lengthy statement read by telephone to W.Va. reporters Tuesday, Manchin said the deal as struck does not do enough to prevent Iran from funding terrorism in the Middle East.

"For me, this deal had to be about more than preventing Iran from acquiring a nuclear weapon for the next 10-15 years. For me, this deal had to address Iran's terrorist actions," Manchin said. "Without doing so would reward Iran's 36 years of deplorable behavior and do nothing to prevent its destructive activities."

Manchin cited the additional resources that could become available to Iran if economic sanctions currently in place are lifted as part of the agreement.

"I cannot in good conscience agree to Iran receiving up to $100 billion in funds that everyone knows will be used, at least in some part, to continue funding terrorism and further destabilize the Middle East," Manchin said. "Lifting sanctions without ensuring Iran's sponsorship of terrorism is neutralized is dangerous to regional and American security."

Manchin now joins U.S. Sen. Shelley Moore Capito, R-W.Va., and U.S. Rep. David McKinley, R-W.Va., in opposing the Iran nuclear agreement.

In a phone interview Tuesday, Capito echoed Manchin's concerns that the sanctions relief in the agreement would enable Iran to further fund terrorism in the region.

Capito, who said she had determined to vote against the deal by early August, added that opposition to the deal among her constituents played a role in her decision.

Capito expressed concern that under the framework of the agreement inspectors wouldn't be able to hold Iran accountable.

"It ends up now that the Iranians can pretty much stall (an inspection) for about 24-28 days. To me, that doesn't get to the transparency and the accountability that we would want," Capito said. "I don't know how we can expect them not to cheat when we can't get in in a timely fashion."

McKinley came out against the Iran deal shortly after it was announced in July.

"We did not win unfettered inspections or a commitment to ending Iran’s nuclear weapons program, and Iran is poised to reap up to $140 billion in sanctions relief. What did we get?" McKinley said in a prepared statement released at the time. "It seems we have once again been misled by an administration more focused on its legacy and earning a Nobel Peace Prize than in securing a peaceful world for the United States and its allies."

Manchin's announcement Tuesday represented a shift in tone from the senator's earlier comments on the Iran deal. In a conference call with West Virginia reporters shortly after the nuclear agreement was first announced, Manchin said he was "hopeful" the deal would prevent Iran from acquiring a nuclear weapon.

But Manchin said Tuesday that he's spent the intervening time speaking with numerous experts and constituents in an attempt to make an informed decision. That decision comes less than a week after multiple national news outlets reported that President Barack Obama has secured enough votes in Congress to ensure the Iran deal goes through.

Though the majority of Congress could ultimately vote against the deal, the votes would not be enough to override a presidential veto, media outlets have reported.

The Iran nuclear agreement would limit Iran's ability to develop nuclear weapons for the next 10-15 years in exchange for lifting billions of dollars worth of economic sanctions. Other nations, including superpowers China and Russia, are also party to the agreement and have indicated they will move forward in lifting sanctions even if the U.S. backs out of the deal, media outlets have reported.

Regardless of what other nations do, Capito said the U.S. has to look out for its own interests and national security moving forward. If the deal goes through, as is expected, Capito said Congress must find other avenues to hold Iran accountable for its actions.

"Obviously, I'm disappointed in what the inevitable results look like they're going to be, and so I think we need to reexamine what our options would be. If Iran is moving forward with terror, can we still impose ... some other kinds of punitive measures that would be effective?" Capito said.

Last week, Manchin held a pair of town hall meetings in West Virginia to hear comments from residents regarding the deal. Comments have indicated that the state's residents overwhelmingly oppose the Iran deal.

Speaking to reporters by phone Tuesday, Manchin downplayed suggestions that the timing of his announcement — now that the deal is veto-proof — is politically motivated.

"People will be saying this is strictly political," Manchin said. "People that know me know that I'll make that tough decision when the facts are lined up in a way that I can defend it. I've always said that if I can't explain it back home I can't support it."