In business, an offer or a proposal that is “on the (bargaining) table” is one that is under consideration or discussion. “To lay that proposal on the table” has been cited in print since at least 1866. Many negotiations take place over a physical table, but an offer made over the Internet can also said to be “on the table.”
 
Other “table” phrases include “bring to the table” (to contribute something), “off the table” (something non-negotiable) and “under the table” (secretly or covertly, often said of a payment).
   
 
(Oxford English Dictionary)
on (also upon) the table : under consideration or discussion.
1884 H. R. Haggard Dawn xlii,  The facts are, so to speak, all upon the table, and I will merely touch upon the main heads of my case.
1915 J. London Let. 25 Aug. (1966) 458   It is..on the table whether or not we shall say ‘it is I’ or ‘it is me’.
1986 Times 1 Aug. 32   The bid is still on the table.
 
25 August 1866, Daily Evening Bulletin (San Francisco, CA), pg. 2, col. 1:
The Board of Supervisors will probably think it their duty to lay that proposal on the table until they have inquired more deeply into the matter.
 
9 June 1903, Manitoba Free Press (Winnipeg, Manitoba), “New Tenders or Supplying Power,”  pg. 6, col. 1:
Mr. Sandison said that he was prepared to lay a bona flde offer on the table and asked if the committee would accept it in preference to any other.
 
Google Books
Andrew Johnson:
Study in Courage
By Lloyd Paul Stryker
New York, NY: Macmillan
1936, ©1929.
Pg. 715:
But there was one old delegate whose conscience was not dead. He moved to lay the proposal on the table.
 
20 June 1946, Springfield (MA) Republican, “Cleveland’s Tribe May Change Hands; Dykes in Picture” (AP), pg. 13, col. 2:
Today, said the News, Sherwin added that “if Mr. Veeck has raised enough money to make it interesting, I haven’t heard about it. We still have no offer on the table.”
 
21 February 1950, Dallas (TX) Morning News, “Miners,” pt. 1, pg. 3, col. 3:
He said the operators have placed “no offer on the table.”
 
10 March 1956, Press- Telegram (Long Beach, CA), “Electric Co. Settlement Hopes Darken,” pg. B3, col. 1:
Westinghouse, Blasier said, has notwithdrawn its offer to accept and “In my opinion the package offer is still on the table.”
 
6 April 1967, Christian Science Monitor, “American Motors reported ready to sell two divisions‎,” Business, pg. 14:
But a spokesman for the firm said: “We are not talking purchase agreement with anybody and no offer is on the table.”
 
Google News Archive
12 September 1967, Owosso (MI) Argus-Press, “Strike Talks On ‘Principle’ Issues” (AP), pg. 32, col. 2: .‎
Malcolm L. Denise, Ford vice president for labor relations, said the company’s initial economic offer is still on the table.