Last week, news leaked about the whistleblower complaint, which alleged that several times during a phone call, Trump asked the Ukraine government to investigate former Vice President Joe Biden, who is running for president against Trump.
The full whistleblower complaint has not yet been made available to the U.S. House Permanent Select Committee on Intelligence, since it is being withheld by Trump's Director of National Intelligence (DNI), who is relying on advice U.S. Attorney General William Barr.
Lamb is requesting that the whistleblower case be released to Congress by Thursday.
“We cannot allow even the possibility to exist that our President used the immense power of that office to protect his own selfish interests, rather than to protect the American people," said Lamb in a statement.
We cannot allow even the possibility to exist that our President used the immense power of that office to protect his own selfish interests, rather than to protect the American people. #PA17 https://t.co/1mFXC22SId pic.twitter.com/awHGlDESsi— Conor Lamb (@RepConorLamb) September 23, 2019
"As lawmakers, we swore an oath to protect and defend the Constitution," said Lamb. "We will get the truth.”
The whistleblower complaint allegations, if proven true, would be a bombshell against the Trump administration. A sitting president asking a foreign government to investigate a political rival is far outside of American Democratic norms.
U.S. House Intelligence Committee Chairman Adam Schiff (D-Calif.) told CNN that impeachment "may be the only remedy" to Trump's refusal to make the complaint and phone call public.
Though more than 130 U.S. House Democrats, including Pittsburgh Rep. Mike Doyle, and one independent have called for the start of impeachment proceedings against Trump, Lamb has not taken that position.
In May, Lamb told WESA he didn't support starting an impeachment inquiry, instead saying he backed several House investigations into the president. On Saturday, USA Today published a story into how many of those investigation efforts have been stalled and blocked by the Trump administration.
Pittsburgh City Paper asked Lamb's office if he has changed his mind on his stance on starting an impeachment inquiry into Trump, but didn't receive a specific response to that question.