Though both Senators deny that there's any kind of spat, it's clear something is brewing. Schumer has been amping up his efforts on the immigration issue, complaining about the closure of a prison that could adversely affect illegals, and authoring the main Democratic immigration bill that could hypothetically (but not realistically) be considered this year.
Kerry has flown to Copenhagen to assure the world that the U.S. -- or at least he -- considers global warming to be a top priority, and pressured Obama to at least mention the issue during his State of the Union address. Problem is, Obama is doing damage control after faltering on health care. There isn't any political space to take on another "thing." If he tries, Obama, and the Democrats, will be so saddled with voter animosity that they won't be able to do anything at all.
What Identity Politics Hath Wrought
America's Second Civil War
Alt-Right's Despicability Doesn't Make 'Antifa' the Good Guys