ClimateWire: A small group of lawmakers could help scrap or spare Congress’ pending effort to impose a price on carbon emissions, but only two of them, the senators from Maine, appear to hold the “balance of power.” Their support in any effort to stem global warming might seem almost automatic. Sen. Susan Collins stomached a lurching helicopter ride between mountains and slept in an Antarctic hut to get a firsthand view of evidence of abrupt climate shifts of the past. Sen. Olympia Snowe …