Talks between the DUP and the Tories "haven't proceeded in a way that DUP would have expected", according to relevant sources.
They said Northern Ireland's Democratic Unionist Party is urging the UK Government to give "greater focus" to the negotiations and that the "party can't be taken for granted".
A day before setting out her legislative measures in the Queen's Speech, Theresa May has yet to secure a deal with the DUP to allow her Government programme to survive a Commons vote.
The talks have been ongoing since the Conservatives failed to win an outright parliamentary majority in a disastrous General Election on 8 June.
Downing Street is confident that the DUP will eventually back Mrs May, but a deal remains elusive.
Adding to the complications is the wider politics of Northern Ireland and the Government's attempts to restore the power-sharing executive at Stormont.
Mrs May met with Ireland's Prime Minister Leo Varadkar on Tuesday. They previously spoke by the phone following Varadkar's election as Taoiseach last week.
Speaking about the recent attack in London, Varadkar spoke of the close ties between the two countries as he met Theresa May, saying that Ireland was "ready and willing" to assist if necessary."
