Harris spoke to reporters on the tarmac at a Florida airport before going on the "Help is Here" tour of the nation on Monday. She responded to a question about whether she would go south with "Not today!" before laughing loudly. "But I have before, and I'm sure I will again", she added.
Republican lawmakers ripped into the former attorney general over her inappropriate reaction to the growing migrant crisis, which escalated after immigration restrictions imposed under Donald Trump were eased. At the same time, media access to border detention centres was curbed significantly.
Sen. Ted Cruz has written to President Joe Biden to criticise him for denying that what was happening at the border was a crisis. He said the Biden administration's refusal to let the press tour the holding facilities was "outrageous and hypocritical".
Steve Guest, a special adviser for communications for Sen. Cruz, tweeted that "apparently, the border crisis is now a laughing matter for the Biden administration", while House Minority leader Kevin McCarthy, a Republican, said that Harris was laughing off a "humanitarian crisis of epic proportions".
A number of Twitter users also expressed their disdain over the vice president's "embarrasing" reaction.