“In this resolution, we are saying we will not allow the power of the Senate to be eroded,” Senator Miriam Santiago, the principal author of the measure, said in a statement last week. The proposed resolution will be lodged in late July, when the Senate reconvenes after a recess.

While a Senate resolution would not be binding on President Benigno Aquino III, it would put pressure on him to allow senators to debate the agreement, which would delay it further, Philippine political experts said.

With national elections due in May next year, politicians are already focusing on who will contest the presidency when Aquino steps down, possibly putting some congressional business on the back burner. The Philippine constitution allows presidents to only serve a single six-year term.

“Aquino is increasingly losing his power to influence Congress,” said political expert Ramon Casiple.

Further delays might raise eyebrows in Washington, experts said, given Manila has been the most vocal critic of Beijing among the claimants to the South China Sea and has urged the United States to be more assertive in pushing back against China’s rapid land reclamation in the waterway.

Senators have said they also want to review an agreement to be negotiated with Tokyo that would allow Japanese aircraft and naval vessels to use bases in the Philippines for refuelling and picking up supplies.

The Senate has ratified previous Philippine defence agreements, including a decades-old security treaty with the United States.

Aquino has said the EDCA only needs executive approval because it’s an addition to existing security arrangements.

To be sure, US-Philippine military ties are already robust.

Philippine military officials say there has been an increase in US exercises, training and ship and aircraft visits in the past year under Obama’s “rebalance” to Asia.

But the EDCA would take the relationship a step further, partly by giving US forces broad access to the Philippines.

Washington for example wants to use Philippine military bases in eight locations to rotate troops, aircraft and ships, the Philippine military chief said in April.

One of those is a base on Palawan island, about 160 kilometres from the Spratly islands, where China’s creation of seven artificial outposts will allow Beijing to project power into the maritime heart of Southeast Asia.

The agreement would also allow the US military to build infrastructure such as barracks, logistic warehouses and fuel depots for its visiting forces.

US Marine Lieutenant Colonel Jeffrey Pool, a Pentagon spokesman, acknowledged that the court process had delayed implementation.

“There have been informal, working-level discussions of potential locations and next steps, but no final decisions have been made nor are there any plans to begin implementing the EDCA until the Supreme Court completes its review,” said Pool.

A Senate resolution on the EDCA would not go unnoticed at the court, the Philippine political experts added.

While the court is independent, it would be taking note of the political winds while also paying attention to concerns over China’s muscle flexing in the South China Sea, they said.

Even if the court ruled the agreement was constitutional, it might say it needed Senate approval, they said.

Theodore Te, the Supreme Court spokesman, said the resolution would not influence the court’s decision, although he noted that the issue of a Senate review of the defence deal had been raised during oral arguments in court.

Any delays in the court decision could send a signal to Beijing that Manila was uncertain about its alliance with the United States, said Ernest Bower, a Southeast Asia expert at the Centre for Strategic and International Studies in Washington.

“If the Supreme Court does not move expeditiously on the EDCA and the agreement is not in place before Obama’s visit, the White House will have to ask whether the Philippines is serious about implementing its treaty alliance with the United States,” Bower wrote recently.