The Irene is the latest vessel to try to breach the 3-year-old embargo on the Palestinian territory in the wake of Israel's deadly flotilla raid in May.
George Mitchell will try to bridge gaps that Palestinian, Israel and American officials failed to close in a frenetic round of meetings in the U.S. last week.
The Obama administration says it is seeking ways to advance the Israeli-Palestinian talks in light of the end of Israel's partial moratorium on settlement building.
France's President Nicolas Sarkozy expressed regret on Monday at Israel's failure to renew a freeze on settlement building on occupied Palestinian land, calling for construction to end.
Despite threats to quit negotiations over Israel's resumption of settlement building, Palestinian president keeps hope of compromise alive; Sarkozy calls for Paris summit.
Netanyahu calls on Abbas to continue sincere, good talks with goal of reaching historic peace agreement between two peoples; Abbas will not announce he is quitting talks.
