It is understood Mr Sharma called Mr Howard,and during that phone call Mr Howard told Mr Sharma that he should proceed with the nomination process.
There are eight candidates for preselection,one of whom will contest the blue ribbon seat for the Liberal Party in a byelection on October 20.
Fairfax Media reported earlier on Thursday that it was understood Social Services Minister Paul Fletcher has called key factional players on behalf of Mr Morrison to urge them to back Ms O'Regan.
Ms O'Regan only had an outside chance of winning preselection until former Business Council of Australia executive Andrew Bragg pulled out,saying the seat should be contested by a female.
Mr Sharma has been struggling to gain enough support because he does not live in the wealthy eastern suburbs electorate.
Two other females have also nominated – NSW Liberals'Women's Council president Mary-Lou Jarvis,who has the backing of the right faction,and rheumatologist Maxine Szramka.
One senior female Liberal said:"Nothing against Katherine,but she is hardly a standout candidate and we are going to hand her a seat like Wentworth just for being a woman."
Another said:"If the Prime Minister was going to insist on a female,he should have made that clear during the nomination process because then you would have got much better candidates."
Sydney MP Alex Greenwich,who is close to Sydney lord mayor Clover Moore,has thrown his support behind a female independent to contest Wentworth.
Licia Heath,an asset manager who has been campaigning for a new public high school in the eastern suburbs,was campaigning with Mr Greenwich in Double Bay on Wednesday.
High-profile doctor and former federal Australian Medical Association president Kerryn Phelps is also considering running for the seat.
But it is understood she is awaiting the result of the Liberal preselection to make a decision.
Liberal polling was said to show that the party could not beat Ms Phelps in Wentworth if it ran a male candidate.
Other contenders for the Liberals are former Wentworth MP Peter King,who has some support from the right of the party,as well as the party's former deputy state director Richard Shields,cardiologist Michael Feneley and digital communications specialist Carrington Brigham.
Labor has preselected investment analyst and Tamarama Surf Club president Tim Murray.