Paul Ryan. AP Photo/J. Scott Applewhite U.S. House Speaker Paul Ryan said on Monday he would step down as chairman of the Republican Party's July convention if presumptive Republican nominee Donald Trump asked him to do so, a Milwaukee Journal Sentinel reporter said on Twitter.

".@SpeakerRyan on whether he'd step down as convention chair if Trump asks: I'll do whatever he asks me to do," Christian Schneider, one of the newspaper's columnists, tweeted.

Ryan also said in the interview he is steadfastly opposed to a third-party candidate, even if it were 2012 party nominee Mitt Romney, Schneider said in another tweet.

(Reporting by Megan Cassella in Washington; Editing by Eric Beech)