The government signed a historic agreement last month with the Revolutionary Armed Forces of Colombia (FARC), Colombia's biggest rebel group, but in a shock move, voters rejected the deal in a referendum on October 2.
"All the negotiators and I have met almost every organisation and we are now digesting more than 500 proposals - and talking with the FARC - to have a new agreement, agreed and approved, by Christmas. That is my goal," Santos told Britain's Observer newspaper.
Since the referendum, Santos has held marathon talks with political figures including former president Alvaro Uribe - who led opposition to the agreement - as well as religious leaders and victims of the armed conflict.
Santos, who won the Nobel peace prize this year for his efforts, said he was happy to meet Uribe "any time" but said "he has been stalling, not allowing the teams to get into real negotiations".
Also Read
Uribe had criticised the deal for granting "total impunity" for rebel crimes.
Santos said: "Some of the proposals are viable and we think the FARC should accept them, but others are simply not viable.
"For example the ones that say there is no armed conflict in Colombia, and that there is no war in Colombia and that there are no victims in Colombia and therefore the transitional justice cannot apply."
The interview comes ahead of a state visit by Santos to Britain on Tuesday, the first ever by a Colombian president, where he will meet with Queen Elizabeth II and Prime Minister Theresa May.
Disclaimer: No Business Standard Journalist was involved in creation of this content