AUSTIN, Texas — The Texas Senate is rejecting House changes to a bill cutting billions in future costs from Houston’s cash-strapped police and firefighter pension plans — meaning both chambers will have to reconcile their differences in conference committee.

Houston Republican Sen. Joan Huffman was the pension proposal’s original sponsor. She said Wednesday that alterations the House made while approving her bill last week were “bad for Houston taxpayers” and “shockingly fiscally irresponsible.”

Plagued by investments that didn’t meet sky-high return expectations, Houston is facing about $8.1 billion in unfunded pension liabilities. The mayor has threatened layoffs if things don’t change.

The bill decreases plan benefits and lowers future investment yield targets. But the House allowed firefighters more time to calculate their pension costs, which Huffman says could threaten the entire plan.