Elizabeth Warren urges citizenship pathway for millions of illegal immigrants.
Warren believes Kamala Harris can achieve immigration reform success.
Warren spoke on CNN's "State of the Union" with Tapper.
Tapper highlighted Biden-Harris administration's unpopular immigration policies.
Border crossings lower now than during Trump administration, Warren says.
Immigration issues need Congress for ultimate resolution, Warren states.
Warren advocates more resources for border and migrant support.
Comprehensive immigration reform includes pathway to citizenship, Warren adds.
Trump focused on illegal immigration during his campaign rallies.
JD Vance criticizes Harris's stance on illegal immigrant citizenship.
Vance claims Harris wants to erode voter protection measures.
Vance warns illegal immigrants to prepare for Trump's potential return.