Five Repubican State Senators have announced their retirements this year — the largest group of Senators to leave the Senate without running for another office since 1971 — and there are likely to be more departures on the horizon. Martha Bark will not be seeking re-election, but Burlington County Republicans are waiting to decide who their eighth district candidates will be before Bark makes her formal announcement. Bernard Kenny, the Senate Majority Leader, is also likely to drop his bid for re-election, rather than face Assemblyman/Union City Mayor Brian Stack in the Democratic primary. Two Democratic Senators from Newark, Ronald Rice and Sharpe James, could retire, instead of facing challenges for renomination. And in Camden County, where Wayne Bryant is expected to seek re-election, circumstances could alter his plans. Insiders say that Republican Senator Peter Inverso has not made a final decision on his 2007 plans.