Mr Lewis informed the Scarlets Chief Executive Stuart Gallacher of developments after last night's meeting and again earlier today and the Union is now awaiting a formal response from the Scarlets.
The offer is in response to the Scarlets' recent declaration of financial difficulties following protracted negotiations involving the sale of Stradey Park and the development of a new home for the team by Carmarthenshire County Council.
"The WRU is well aware of the financial difficulties surrounding the Scarlets' bid to move to a new ground within the town," said WRU Group Chief Executive Roger Lewis. "The Union and the club have been in constant negotiation over a long period of time to find a way to ensure that professional rugby not only survives, but thrives, in West Wales.
"The long-term future of the Scarlets, as with all our Regions, is of paramount importance to the game in Wales and the WRU will do all it can to secure that and assist the Regions in their ambitions for success both domestically and in Europe.
"The WRU is committed to working with the Scarlets to enable them to reach their goals - not only for rugby within their region, but also on a national scale.
"The WRU Board of Directors met twice in three days to consider the parameters of the offer to buy the lease at Stradey Park to release funding for the region to continue to operate at the top level.
"The Union will now be backing the Scarlets' bid, in conjunction with Carmarthenshire County Council, to build a new home for the team on the outskirts of the town.
"I will be writing to the Welsh Assembly to keep them up to speed with our dealings with the Scarlets and our feelings over their long term future. It is vital that we find a way for professional rugby to operate on a firmer financial footing in the heartland region of West Wales."
The Union expects a response from the Scarlets before the end of the week.