By Michelle Martin and Noah Barkin BERLIN (Reuters) - German Chancellor Angela Merkel tried to restore calm to her coalition government on Sunday after tensions tied to bailout negotiations with Greece burst out into the open, laying bare resentment among the highest-ranking ministers in her cabinet. Schaeuble, the influential 72-year-old minister who has pressed a hard line with Greece for months, was unrepentant and even suggested that he would be prepared to step aside if Merkel objected to his negotiating tactics. Schaeuble's hardline stance and deep scepticism towards Greece in the German population has pushed her towards a tough line at a time when Gabriel's SPD and key European partners like France favoured a more conciliatory approach.