The two Tory leadership candidates issued their personal manifestos yesterday as ballot papers were posted out to the party's 300,000 members.
Both Iain Duncan Smith and Kenneth Clarke sought to play to their respective strengths as they unveiled their policy ideas and "mission statements" ahead of next month's closing date for the poll.
Mr Duncan Smith stressed his opposition to the euro as the factor that would enable him to lead a united party with "clear leadership and direction".
By contrast, Mr Clarke reiterated his stance that the single currency ought to be left to a referendum and should be put to one side so that the Tories can attack Labour on the economy and public services.
The Conservatives' rank and file have until 11 September to return their ballots, although in practice the contest is likely to be decided in the next few days, when most people will vote.
A new leader will be announced on 12 September, once the Electoral Reform Society, which is conducting the election, has checked and handed over the results to Conservative Central Office.
The coming week will be crucial to the outcome of the contest as the one and only television debate between the two rivals takes place on BBC2's Newsnight tomorrow night. The live debate will follow the first of a series of eight official hustings meetings organised across the country by the national party.
Yesterday's launches revealed in detail the contrasting styles and policy approaches of Mr Clarke and Mr Duncan Smith on everything from the euro to morality.
In his 10-page document, titled Towards a Conservative Revival, the former Chancellor outlines a series of Conservative principles, such as freedom and opportunity, that he declares should be reapplied to reflect modern life.
He points out that the party has suffered "two colossal electoral defeats" and makes a less-than-veiled attack on William Hague's lurch to the right and the "bandwagon" approach to policy.
Both men refer to the need to cut back on bureaucracy for public services and to reduce the size of the state. But Mr Clarke stresses his belief in "civic capitalism" while Mr Duncan Smith emphasises that he prefers a "welfare society" to the welfare state.
Mr Duncan Smith makes no criticism of Mr Hague and, in fact, highlights his own campaigning work across 100 constituencies during the last general election.
The Conservative defence spokesman outlines an unashamedly right-wing agenda with a radical tinge, promising to roll back the "ration book state" of Labour.
Whereas Mr Clarke refers to the need to shift the party back to the "centre ground", Mr Duncan Smith refers to the need to occupy what he calls the "common ground". This difference underlines his own belief that Margaret Thatcher did not win three elections in a row by championing centrist, consensus politics.