By Tim Reid and Nathan Layne PHOENIX, Ariz. (Reuters) -Republicans made modest gains in U.S. midterm elections but Democrats did better than expected, leaving control of Congress and the future of President Joe Biden’s agenda unclear on Wednesday morning. Many of the most competitive races were too close to call and Republicans acknowledged that the election was not producing the sweeping “red wave” victory they had sought. The results appeared to show voters punishing Biden for presiding over an economy hit by steep inflation, while also lashing out against Republican moves to ban abortion. A…