Pat McFadden MP said the suspension of services was causing "huge inconvenience" for people already struggling with congested roads and rammed trains.
The West Midlands Metro has ground to a halt and could be suspended for weeks to come after cracks were identified on some trams.
Shadow City Minister Mr McFadden says the issue is a hammer blow to the region's economy and has asked for assurances that a "proper investigation" takes place to find out what went wrong.
The Labour MP for Wolverhampton South East said: "The suspension of the Metro is causing huge inconvenience.
"The roads are already congested enough and to lose this vital connection at such a busy time of year is a blow to passengers and to the regional economy.
"It is vital that there is a proper investigation as to what went wrong here and that the problems be fixed as soon as possible to get this service back on the rails.”
Earlier this week the Express & Star revealed that cracks were first found in a tram in December 2019. It was temporarily taken out of service and fixed, but more cracks in vehicles were spotted in June this year, prompting bosses to launch a repairs programme.
All services have now been suspended for a minimum of four weeks after it emerged fresh repairs were urgently required.
The West Midlands Combined Authority has asked Transport for West Midlands (TfWM) to conduct an independent review into the governance of the Metro.
TfWM interim managing director Anne Shaw said the review would be carried out by an "industry expert", and will look into the way the programme is managed and delivered through a "wholly owned company".
"This is to ensure TfWM has the right structures in place to hold both Metro programme delivery and operations to account," she added.