text:  Live from NPR News, I'm Lakshmi Singh. President Biden is expected to hold a solo news conference today at the conclusion of the NATO summit. The moment will be a pivotal test for Biden's ability to clearly say what he means to say as he resists growing calls from his party to withdraw from the presidential race. Some eyes are on his VP. NPR's Asma Khalid describes the GOP scrutiny on Vice President Kamala Harris.