Two Honolulu City Council members have submitted separate proposals to lift a planned cap in a bill pertaining to how much more general excise tax surcharge dollars could be used for the city’s $6.57 billion rail project.

Bill 23, which would allow the city to extend Oahu’s 0.5 percent surcharge by five years, through Dec. 31, 2027, is up for the second of three necessary approvals from the Council today.

Councilwoman Kymberly Pine’s proposed floor draft would remove the cap and add a few amendments.

Councilman Brandon Elefante’s proposed draft would do away with the cap and delete language requiring the Honolulu Authority for Rapid Transportation to submit additional reports.

HART officials and rail supporters say the 20-mile guideway, 21-station project cannot be finished as planned if the extension is not passed as is. Critics counter that a move to limit how much HART gets — or rejection of the extension altogether — would rein in rising costs, even if it means shrinking the project.

Officials with the Federal Transit Administration, meanwhile, have warned that tinkering with the current project or its funding could be considered a breach of its full funding grant agreement and have threatened to pull at least a portion of the $1.1 billion promised for the project if HART fails to secure the funding for the city’s share.

Despite the warning, Council Chairman Ernie Martin in October introduced his version of Bill 23, which would cap HART’s take from the tax surcharge at $910 million. That plan was given preliminary approval by the Council Budget Committee and is the version before the Council today.

Extending the surcharge is projected to bring in about $1.5 billion, assuming a growth rate of 4 percent. Martin wants any leftover money to be used by the city for affordable-housing construction, a change that would need the Legislature’s backing.

Pine and Elefante both said Tuesday that placing a cap on HART would jeopardize the project.

Pine said that when H-3 freeway and the two other Windward highways were proposed, no one suggested that the project stop midway.

Elefante said any plan to shorten the route, as some have proposed, would also jeopardize funding and be unfair to Central and West Oahu residents who need a rail line to go into downtown Honolulu.