WASHINGTON (Reuters) -The risk of a partial U.S. government shutdown beginning next week is rising as congressional Democrats and Republicans hit an impasse over how to continue to fund the federal government. A shutdown could affect financial markets by limiting the operations of financial regulators and delaying the publication of key economic data. How might markets react? Historically, markets have tended to shrug off shutdowns. However, this time could be different. A prolonged shutdown risks dela ...