Speaker Nancy Pelosi (D-Calif.) is sidestepping specifics on the shape and timing of a health care overhaul as she tries to nail down details of a plan that can muster a majority vote in the House.“When we’re ready, I’ll tell you where we’re going to be,— Pelosi told reporters Thursday at her weekly press conference.But with House Democrats aiming to produce a unified draft of the measure next week, Pelosi made clear her preference on one hot-button issue: a public insurance option pegged to Medicare rates. “It saves the most money,— she said, indicating the burden will be on those who prefer another approach — for example, a costlier model in which the plan would negotiate rates with providers — to make their case. “If we don’t take the full benefit of the savings, then what are our opportunity costs? Where else would we go to bend the curve and to pay for the legislation?— she said.Democrats huddled for about two hours Thursday morning to discuss the issue and hear from two policy experts on the relative benefits of a public insurance option versus health care cooperatives, an approach advocated by some moderates and contained in a competing Senate health bill by Finance Chairman Max Baucus (D-Mont.).Pelosi said she sensed an emerging consensus from that session that another alternative favored by some moderates — a “trigger— approach, in which a public option would only kick in as a fallback — is “an excuse for not doing anything.—