Key mediator Egypt expressed scepticism Wednesday as more details emerged of the proposal meant to bridge gaps in ceasefire talks between Israel and Hamas, a day before negotiations were expected to resume in Cairo. The challenges around the so-called bridging proposal appear to undermine the optimism for an imminent agreement that U.S. Secretary of State Antony Blinken carried into his latest Mideast visit this week. Diplomatic efforts had redoubled as fears grow of a wider regional war after the recent targeted killings of Hamas and Hezbollah leaders, both blamed on Israel, and threats of re…