By Susan Cornwell and Makini Brice WASHINGTON (Reuters) – Democrats in the U.S. Senate on Tuesday took the first step toward fast-tracking President Joe Biden’s proposed $1.9 trillion coronavirus aid bill without Republican support. The Senate voted along party lines, with Democrats edging out Republicans 50-49, to open debate on a fiscal 2021 budget resolution with coronavirus aid spending instructions. Using this strategy unlocks a legislative tool needed for Democrats to enact Biden’s package in the face of Republican opposition. Republicans have pushed back on Biden’s $1.9 trillion price t…