One of the moderate Democrats in the U.S. Senate said this week she won’t switch parties. “No. Why would I do that?” Sen. Kyrsten Sinema (D-Ariz.) said during an interview with Politico. Sinema has faced harsh criticism from some fellow Democrats. A handful have said she’s already a Republican. The critics argue the first-term senator and Sen. Joe Manchin (D-W.Va.) are blocking much of President Joe Biden’s agenda. Sinema and Manchin have stood firm against some of the more radical proposals, including a bill that would have cost $3 trillion and had no Republican support. Democrats barely control the House of Representatives after a weak 2020 election. The party holds 50 seats in the upper chamber. It controls the Senate because Vice President Kamala Harris, the president of the chamber, is a Democrat. She can cast tiebreaking votes. Manchin has also said recently he wouldn’t switch parties. He’s described himself …