By Jason Lange WASHINGTON (Reuters) – One in four U.S. Democrats say their party did not take full advantage of its grip on the White House and Congress last year, a Reuters/Ipsos poll found, in a troubling sign for their voters’ enthusiasm in this year’s congressional elections. The finding echoes concerns raised by moderate Democratic members of Congress whose seats the party will have to defend in the Nov. 8 election if it wants to keep its majorities. They said the party has paid too much attention to its failures and not enough to successes like the $1 trillion infrastructure bill passed …