ABC's Jonathan Karl reports: A high-level GOP source tells me that party leaders have essentially given up on Republican Senate candidate Joe Miller and are now banking on a victory by write-in candidate Lisa Murkowski as the best bet for Republicans to keep the Alaska Senate seat. Murkowski defied party leaders by running a write-in campaign after she lost the Republican primary last month. But with Miller's campaign faltering, the source tells me that Republican leaders are now worried that Democrat Scott McAdams has a shot of winning and that Murkowski may be the only way to stop him. It's...