LANSING, Mich (WLMI)  The American Red Cross is always in need of blood supplies—Hurricane Irene has made that need even more urgent.  But now—a possible strike by nearly 300 Red Cross workers in Michigan means upcoming blood drives could become a REAL challenge.Monica Stoneking, spokesperson for the American Red Cross-Great Lakes Region, says the unions representing 280 workers in Michigan notified the non-profit that they are prepared to go on strike on Wednesday, September 7^th if a new contract isn’t reached.  Stoneking says a major sticking point is health benefits--the Red Cross offered the unions a plan that pays 90% of premium amounts for employees and 80% for dependents.  The unions turned-down the offer.  Stoneking says negotiations between the two sides are ongoing in hopes of reaching an agreement by next Wednesday.  She says contingency plans are in-place to keep upcoming blood drives fully-staffed in the event of a strike.