Local Government Secretary James Brokenshire has written to all the region's 20 councils, 18 of which support a 'One Yorkshire' devolution deal, to say the Government is "not prepared" to discuss the proposals if they include any of the authorities which make up the Sheffield City Region.
Dan Jarvis was elected Sheffield City Region (SCR) Mayor in May on a pledge to pursue a transfer of money and powers from Westminster to a One Yorkshire authority and also received a letter.
Two of the SCR councils - Doncaster and Barnsley, back the idea, although Sheffield and Rotherham are opposed.
That division has left Mr Jarvis with few powers or money and devolution in the region up in the air while Ministers considered the One Yorkshire plans.
Mr Brokenshire's move comes with One Yorkshire backers set to meet on Thursday to agree on a structure of how a regional devolution deal could work, including the powers of any potential Yorkshire mayor, in what promises to be a significant step forward in their plans.
In the letter obtained by The Yorkshire Post, which was also sent to North Lincolnshire and North East Lincolnshire councils, Mr Brokenshire pointedly referred to a "short outline" of proposals, which have in contrast been described by One Yorkshire supporters as "detailed and concrete", which were submitted to the Government in March.
The Local Government Secretary went on: "We are prepared to consider any proposal submitted to us, on the same criteria that we have used to consider devolution proposals elsehwere.
"However, as you know the Government has always been clear that the first step to any devolution deal across Yorkshire is the full implementation of the 2015 Sheffield City Region devolution deal."
Mr Brokenshire added: "Until the Sheffield City Region deal is fully implemented, the Government is not prepared to enter into any discussion about wider devolution arrangements that would include some or all of the SCR authorities."
A West Yorkshire Combined Authority spokesperson said: "The One Yorkshire proposal has the cross-party support of 18 authorities, ready to deliver a devolution deal offering huge benefits for the region and the wider UK economy.
"With the constructive support of the Government an agreement can be in place and a Mayor for One Yorkshire elected by 2020. Yorkshire Leaders will discuss the Secretary of State's letter and the progression of the One Yorkshire devolution deal at their regular meeting on Thursday."