In November, 1845, he was sent as minister to Mexico by President Polk, to adjust the difficulty caused by the annexation of Texas to the United States. His instructions to 1) obtain Mexican recognition of the Rio Grande as the border between Texas and the United States; 2) offer American forgiveness of the claims by U.S. citizens against the Mexican government; 3) purchase the New Mexico area for $5 million; and 4) purchase California at any price. The mission failed when the Mexican government refused to accept his credentials. The United States declared war on Mexico on May 13, 1846, and Slidell returned in January 1847 and resigned.
John Slidell was not received by Mexico.
The Slidell mission was when James K. Polk sent John Slidell as an envoy, to Mexico as a minister in 1845. The Mexican people didn't even permit him to offer his proposition.
The United States bought California (and New Mexico) for $15 million from the Mexican government.Read more: How_much_was_California_bought_for
Polk sent former Congressman and lawyer John Slidell to Mexico and make an offer to buy California for $30 million. He also wanted to settle the dispute about the location of the Texas border. I do not know if New Mexico was discussed.
Sell Alta California and Nuevo Mexico and recognise the Rio Grande as the southern border of the United States.
California and New Mexico
The original offer was $30 million
California and New Mexico didn't exist. Mexican independence happened in 1810. California didn't exist as California until 1850. The mission system in California changed hands from Spain to Mexico.
The Mexican Cession or the Mexican States of Alta California and Nuevo Mexico.
The acquisition of New Mexico and California is called the Mexican Cession of 1848. The Mexican Cession also included California, Nevada, and Utah.
Mexico lost much of its territory. Taxes were lowered which were high under the Mexican government.
The only land that was stolen from Mexico was Texas the others were fought for or bought!